Testacea

“ Value of Testacean Fossils in Classification.—It will be observed that in the foregoing allusions to organic remains, the testacea or the shell-bearing mollusca are selected as the most useful and convenient class for the purposes of general classification. In the first place, they are more universally distributed through strata of every age than any other organic bodies. Those families of fossils which are of rare and casual occurrence are absolutely of no avail in establishing a chronological arrangement. ”

“ Their general dip is about 10°, varying in direction from south-east, near Maungaharuru, to south and south-west as their northern termination is reached. Fossils are plentiful, but, as is usually the case when embedded in Papa, are of so fragile a nature that it is very difficult to preserve them. I obtained eighteen different species of Testacea from these beds in different parts. In this formation we first see signs of local disturbance, which is not continued, as far as I am aware, into the overlying one. ”

“ Some of the species also, the identity of which with the living would not be disputed by any conchologist, are nevertheless distinguishable as varieties, whether by slight deviations in form or a difference in average dimensions. Since Mr. Searles Wood first described the marine testacea of the Crags, the additions made to that fossil fauna have not been considerable, whereas we have made in the same period immense progress in our knowledge of the living testacea of the British and arctic seas, and of the Mediterranean. ”

“ In all cases alike the Testacea have, like plants, the head downwards. The reason for this is, that they take in their nourishment from below, just as do plants with their roots. Thus the under parts come in them to be above, and the upper parts to be below. The body is enclosed in a membrane, and through this the animal filters fluid free from salt and absorbs its nutriment. In all there is a head; but none of the parts, excepting this recipient of food, has any distinctive name.
Part 8 All the Crustacea can crawl as well as swim, and accordingly they are provided with numerous feet. ”

“ Testacea aut fulva, antennis pallide rufis, abdomine subpubescente, alis cinerascentibus, costa basali nigra. Var. β. Abdomine piceo basi fulvo.
Male and Female. Testaceous or tawny, slightly setose; antennæ pale red, 3rd joint conical, about twice the length of the 2nd; abdomen slightly pubescent; wings greyish, black along the costa towards the base; veins black; discal transverse vein straight, upright, parted by a little more than its length from the border, and by more than its length from the præbrachial transverse. Var. β: Abdomen piceous, tawny towards the base. ”

“ The variety of species of Testacea contained in the recent calcareous marl of Scotland, before mentioned, is very small, but the abundance of individuals extremely great, a circumstance very characteristic of freshwater formations in general, as compared to marine; for in the latter, as is seen on sea-beaches, coral-reefs, or in the bottom of the seas examined by dredging, wherever the individual shells are exceedingly numerous, there rarely fails to be a vast variety of species. ”

“ Testacea, gracillima, capite subelongato, antennis pallide rufis basi nigris, thorace antico attenuato, abdomine lineari apicem versus tumido, femoribus intermediis subincrassatis, tibiis intermediis nigris, tarsis intermediis albis apice nigris, alis pallide fuscescentibus, basi fasciaque cinerascentibus.
Male. Testaceous, very slender; head somewhat elongated; antennæ pale red, black at the base; thorax long, attenuated in front; abdomen linear, tumid towards the tip, narrower and much longer than the thorax; legs very long; fore legs much shorter and more slender than the others ”

“ The ova of the other oviparous tribes are either perfected externally, as in the case of fishes, or they are concocted or matured, as in the instance of testacea, crustacea, and spiders. Testaceous animals lay their eggs amidst froth ”

“ The analogy of the whole group of testacea to the European type is very marked, whether we refer to the large development of certain genera in number of species or to their size, or to the suppression or feeble representation of others. The indication also afforded by the entire fauna of a climate not much warmer than that now prevailing in corresponding latitudes, prepares us to believe that they are not of higher antiquity than the Older Pliocene era. [163-A]
Fig. ”

“ In the system of Linnæus, the soft portions are first arranged under the general designation of "Vermes Mollusca," and described without regard to the presence, absence, or character of the shells; and then the shells are separately characterized under the appellation of "Vermes Testacea," without any further notice of the animal, than an indication of the genus to which it belongs; thus the animal of Cypræa is said to be a Limax, and that of Tellina a Tethys. ”

“ Nucula oblongoides (hyperbarea) .
6. Of extinct crag forms, those marked with an asterisk, are new species of Mr. Wood.
From the beds at Bridlington, Mr. Lyell [19] enumerates 35 species of testacea, of which 20 were living forms, and 26 species common to the mammaliferous or Norwich crag. I have had an opportunity of examining a collection from this locality belonging to my friend Mr. Bowerbank, who, with his accustomed liberality, has permitted me to make use of it. It includes 28 species. ”

“ Testacea, vertice pectorisque fasciis duabus piceis, antennis supra nigris, abdominis lateribus fasciis duabus subtrigonis apiceque nigris, alis cinereis.
Male. Testaceous. Vertex and mouth piceous; epistoma with a piceous line on each side; third joint of the antennæ black above; abdomen black along each side and at the tip, and with two black bands which are angular in front; wings cinereous. Length of the body 31⁄2 lines; of the wings 6 lines.
Gen. Eristalis, Latr.
69. Eristalis splendens, Leguillon, Voy. aut. du Monde; Macq. Dipt. Exot. 11. 2. 49. 28.
Inhabits also Solomon's Islands. ”

“ For compared with animals they resemble plants, compared with plants they resemble animals, so that in a sense they appear to come into being from semen, but in another sense not so, and in one way they are spontaneously generated but in another from their own kind, or some of them in the latter way, others in the former. Because their nature answers to that of plants, therefore few or no kinds of testacea come into being on land, e.g. ”

“ In most of the lower orders of animals there is a periodical development of the testicles in the male, corresponding in time with that of the ovaries in the female. As the ovaries enlarge and the eggs ripen in the one sex, so in the other the testicles increase in size, as the season of reproduction approaches, and become turgid with spermatozoa. The accessory organs of generation, at the same time, share the unusual activity of the testicles, and become increased in vascularity and ready to perform their part in the reproductive function. ”

“ Fishes and serpents have no testes, but in place of them they have two veins, which run from the renal region to the genitals. The bird known as the “buteo,”354 has three testes. Man is the only creature in which the testes are ever broken, either accidentally or by some natural malady; those who are thus afflicted form a third class of half men, in addition to hermaphrodites and eunuchs. In all species of animals the male is more courageous than the female, with the exception of the panther and the bear. ”

“ The testes are solid ridges formed by the growth of the lining cells of this part of the body-cavity; the cells mature into spermatozoa, which break off and float freely in the coelomic fluid. At the breeding season the whole tail may be crowded with masses of spermatozoa, which are kept in a more or less regular circulation by the ciliated cells lining the body-wall. The vas deferens opens internally into the space where the spermatozoa lie, and at the other end into a vesicula seminis, which opens to the exterior. ”

“ The openings of the generative organs will be found in the male on the basal segments of the last pair of legs, while in the female they occupy the same position on the legs of the last pair but two. The testis of the male lies in the thorax, just below the heart. The ovary, which has the same position in the female, is usually much more conspicuous, and from its red colour in the cooked Lobster it is known as the "coral." On the under-side of the thorax of the female, between the last two pairs of legs, is a three-lobed structure enclosing a cavity known as the "sperm-receptacle." ”

“ Looking at Plate 2, you will see the man's sex machinery. The testicles are to a man what the ovaries are to a woman. They are two sacs held in a bag of rather thin loose skin called the scrotum, and it is here that the sperm (spermatozoa) or germ of life grows. Just how no one really knows. The spermatozoa are very tiny and the testicles hold many thousands of them. Under the microscope they show a sort of head and tail like a pollywog. They are very much alive and move by a rapid wiggling of the tail part. ”

“ TESTACEOUS. (Testa, a shell.) Shelly. Testaceous Mollusca, are soft animals having shells. A testaceous operculum is one composed of shelly matter.
TETRACERA. Bl. The first family of the order Polybranchiata, Bl. containing no genera of testaceous mollusca.
TEXTILIA. Sw. A sub-genus of Conus, consisting of Conus bullatus, &c. Sw. Malac. p. 312.
TEXTULARIA. Defr. A genus of microscopic Foraminifera.
THALAMUS. Montf. A genus described as resembling Conilites, but curved and granulated.
THALLEPUS. Sw. A genus of "Aplysianiæ," Sw. thus described: "Body more slender and fusiform;" ”

“ Then come a number of intermediate species, each with progressively smaller and thinner shells, till at length we reach the testacella, which has only a sort of limpet-shaped shield on his tail, so that he is generally recognised as being the first of the slugs rather than the last of the snails. You will not find a testacella unless you particularly look for him, for he seldom comes above ground, being a most bloodthirsty subterraneous carnivore who follows the burrows of earthworms as savagely as a ferret tracks those of rabbits ”

“ In the lower (or simpler and possibly degenerate Metazoa) the reproductive or germinal tissue consists of a few cells, sometimes in a group, sometimes scattered and sometimes migratory; in the vast majority of the Metazoa the germinal tissue becomes aggregated in distinct organs, of which those that give rise to ova or female gametes are known as the ovaries, and those that give rise to the spermatozoa or male gametes are known as the testes. The ovary and the testis are the primary reproductive organs ”

“ In many insects the testes are not composed of tubes (follicles) , but of button-like bodies, each of which has its own duct.
The color of the testes is usually white, but they may be orange (Decticus) , yellowish green (Locusta viridissima) , or deep yellow (Chrysopa) .
The testes of Asilid flies are enveloped by a common dark-red membrane rich in tracheæ, like that in Lepidoptera which clothes the separate testicular follicles. The two testes of Calliphora are enveloped by an orange-yellow capsule, outside of which is a special membrane formed by the fat-body. (Cholodkowsky.) ”

“ Insects are SEXUALLY DISTINCT; their sexual glands are in pairs and have a tubular structure, but the testicular tubules are united together by a capsule into an oval testicle; exceptionally, also, the excretory canals are double, as also the sexual orifices; usually the paired canals unite into a single oviduct or spermatic duct which terminates at the posterior end of the body after receiving the products of various glands. ”

“ Indeed, the number of species of Arion diminishes as we leave that province, though one extends beyond the borders of Europe into Siberia. The same number of species, viz. five, occur in Germany and in England. Testacella—a slug-like mollusc—which lives underground on earthworms, and of which genus three species, viz. T. maugei, T. haliotidea, T. scutulum, are known to inhabit the British Islands, is another Lusitanian animal. All the species are confined to Western Europe and North Africa; they do not even reach Germany or Switzerland. ”

“ A particularly fine example of the specific action of gland secretions upon cells of specific structure is supplied by such cases of hermaphroditismus verus as that, for instance, in which the bullfinch is found to have a testicle on one side and an ovary on the other. These peculiar animals have on the one side male, and on the other female, plumage, each being delimited accurately, and without any transition, along the middle line of the body. ”

“ Like the Snails, they are fond of damp localities, and at times become great pests to farmers in devouring the young shoots of the growing corn. Testacella, which is found in this country, differs from the Slugs in having an external shell at the tail-end of the foot. It is not slimy, and lives under ground, feeding upon earthworms. ”

“ It is incorrect to suppose, as has been held by some{121} theorists, that one testicle give rise to male spermatozoa and the other to female spermatozoa, for both male and female offspring have been produced from the same male parent after one testicle or the other has been removed. The same is true in cases in which either ovary has been removed from the mother; that is, male and female offspring are produced from mothers in whom either ovary has been removed. ”