Myriapod

“ The young myriapod and the young spider are found immediately after they have emerged from the egg to present most of the features of the mature insect, and so also the immature grasshopper and squash-bug resemble the perfect insect in nearly everything but size and the absence of fully developed wings. ”

“ The liquefaction and decay of this mushroom come on so quickly that it is not usually infested with larvæ which do not have time to develop before the mushroom is reduced to a shapeless mass. The most common organism found is the myriapod, a thousand-legged worm, which often finds its way between the gills and stem. ”

“ Originally the body is composed of a congeries of cells, segment after segment being added, exactly in the same manner as in the case of the Annelida, with which in structure they closely agree, being adapted, however, to live on land. The Annelida seem then to be the ancestors of the Myriapoda, Insects, and Spiders, the Myriapoda retaining much of the Annelid structure through life, whereas the Insect is an Annelid or Myriapod only when in a larval or undeveloped condition. That the development of the different kinds of insects has been gradual. ”

“ With the next process the formation of the young Myriapod may be said to begin. A strip along the length of the oval-shaped egg is thickened, and this thick mass of cells represents the future ventral surface of the animal. The rest of the thin layer of cells already mentioned just below the shell will form the shell or exoskeleton of the future animal. The thick strip of cells at the ventral surface has by this time split into layers, so that, resorting to our microscope again, a section through the short axis of the oval-shaped egg—a transverse section—will show us ”

“ The Myriapods are worm-shaped creatures, breathing by means of air-tubes, and furnished with a number of limbs closely resembling each [121] other. There are two groups: the Centipedes and the Millepedes. The former have the body flattened, with one pair of appendages to each segment, the first pair being modified into piercing poison-organs, and they feed on living prey. The body of the Millepedes is round, with two pairs of appendages to each segment; they have no poison-organs, and their food consists chiefly, if not entirely, of vegetable matter. ”

“ They appear to stand out the strong, well-marked, first link of that long chain which bridges over the mighty gulf which rolls between the creeping worm and the flying insect. The Myriapod is the lowest articulate animal, the Annelid the highest annulose—i. ”

“ Although this monograph of a single faunic group is not the place for a discussion of the history of the classification of the Myriapoda, yet it has seemed necessary to make this brief notice of and comparison between the works of the more recent authorities, before introducing what appears to the author to be the natural arrangement, which has been gradually developed by the various efforts; each adding something, each pushing forward a little towards the truth. ”

“ Of the creeping, wingless creatures, which can ever be found beneath rocks, rails, chunks, and especially beneath those old decaying logs which are half buried in the rich vegetable mould, the myriapods, or “thousand-legs,” deserve more than a passing notice. They are typical examples of that great branch of the animal kingdom known as arthropods, which comprises all insects and crustaceans. Each arthropod has the body composed of rings placed end to end and bearing jointed appendages, and in the myriapods each ring and its appendages can be plainly seen ”

“ MYRIAPODA (Gr. for “ many-legged ”) , arthropod animals of which centipedes and millipedes are familiar examples. Linnaeus included them in his Insecta Aptera together with Crustacea and Arachnida; in 1796 P. A. Latreille designated them as Myriopoda, making of them, along with the Crustacean Oniscus, one of the seven orders into which he divided the Aptera of Linnaeus. Later on J. C. Savigny, by study of the mouth-parts, clearly distinguished them from Insects and Crustacea. In 1814 W. E. Leach defined them and divided them into Centipedes and Millipedes. ”

“ Pliny tells us of a marine Scolopendra, but this was most probably a species of marine worm.
Linnaeus included Myriapods among the Insects; and the writers after him till the beginning of this century classed them with all sorts of Insects, with Spiders, Scorpions, and even among Serpents. It was Leach who first raised them to the importance of a separate class, and Latreille first gave them the name of Myriapoda, which they have retained ever since.
Myriapods are terrestrial animals, crawling or creeping on the ground or on logs of wood, or even under the bark of trees. ”

“ The Myriapods do not exercise so much direct influence on human affairs as do some other classes of animals; for instance, Insects. They include no species which is of direct use to man, like the silkworm or the cochineal insect, and they are of no use to him as food. It is true that they are injurious to his crops. For instance, the species of Millepede known as the "wire worm" [10] is extremely harmful ”

“ In the myriapods the dorsal trunk has as many segments as there are joints of the body. One of the millepeds has not less than one hundred and sixty. Centipeds have generally twenty-one segments, and besides the pair of valves for each joint there is given off a pair of arteries. ”

“ The mode of progression in the Myriapods differs considerably, as might be expected in a class in which the number of legs varies to such an extent. The swiftest among them are the Scutigeridae with their long spider-like legs. The Scolopendridae are also able to move with considerable rapidity, and are also able to move tail forward almost as well as in the ordinary manner. Where there are such a number of legs it becomes a curious question as to the order in which the animal moves them ”

“ On glancing over the Chilopoda it will be seen that, as we descend the scale, the number of segments in the body constantly increases—or, in other words, the distinctive character which separates the Myriapods from the Hexapods and Crustacea, and allies them to the Annelids,—the multiplicity of segments, the absence of cephalization—is exaggerated. On applying this principle, it will be at once perceived that the Polydesmidæ must be placed above the Iulidæ, and the Glomeridæ, Leach (of Newport) , be still higher, and thus be thrown next to the first order. ”

“ When we think of the diet of the Amphibia we are reminded of the other prominent representatives of land life at the time. Snails, spiders, and myriapods crept over the ground or along the stalks of the trees, and a vast population of insects filled the air. We find a few stray wings in the Silurian, and a large number of wings and fragments in the Devonian, but it is in the Coal-forest that we find the first great expansion of insect life, with a considerable development of myriapods, spiders, and scorpions. ”

“ They appear to belong to the mouth-parts. The internal anatomy will be found to be, if examined, much like that of insects and can be studied from the account of the anatomy of the water-scavenger beetle and butterfly larva. Compare the Myriapods with the Hexapods or true insects. What are the points of resemblance? what are the points of difference?
The Myriapoda are land-animals breathing by means of tracheæ like the insects. In them the body-segments [Pg 227] are nearly uniform in character with the exception of the head, which, as in the insects, bears the mouth-parts and antennæ. ”

“ The poorly developed nervous system and organs of special sense, the short weak legs, and the weak muscular and large intestinal development, all point to the vegetable nature of the food of this order and the associated sluggish habits, which indications the total absence of offensive armature confirms.
M. Brandt (Recueil) divided the Myriapoda into Myriapoda manducentia and Myriapoda sugentia. The former comprises all those which are provided with mandibles or jaws for seizing or devouring food. ”

“ On the whole, we may say that the Chilopoda are most largely represented in the hotter climates, where they find a more abundant diet in the rich insect life of the tropical and semi-tropical countries. The more brightly-coloured Myriapods, too, are for the most part inhabitants of the warmer countries. The ease with which they are introduced into a country in the earth round plants, and in boxes of fruit, may account to a great extent for the wide distribution of the various species in different countries. ”

“ At the head of the Myriapods, and pre-eminent from a superiorly-developed organisation, stands the genus Cermatia: singular-looking objects; mounted upon slender legs, of gradually increasing length from front to rear, the hind ones in some species being amazingly prolonged, and all handsomely marked with brown annuli in concentric arches. These myriapods are harmless, excepting to woodlice, spiders, and young cockroaches, which form their ordinary prey. They are rarely to be seen ”

“ Such a discovery renders all speculation as to the origin of true insects premature, because we may feel sure that all the other orders of insects, except perhaps hymenoptera and lepidoptera, were contemporaneous with the highly specialised beetles.
The less highly organised terrestrial arthropoda—the Arachnida and Myriapoda—are, as might be expected, much more ancient. A fossil spider has been found in the Carboniferous, and scorpions in the Upper Silurian rocks of Scotland, Sweden, and the United States. Myriapoda have been found abundantly in the Carboniferous and Devonian formations ”

“ A few species of myriapods are known to be luminous; perhaps more species than are now known to possess this function actually possess it for short periods during the year, probably during the height of the mating season. In some myriapods, the luminosity seems to be developed in a secretion which is ejected from pre-anal glands, while in others it is located in organs on the body of the creature, as in the insects. ”

“ The only groups of articulates wholly air-breathing are the myriapods, insects, and arachnids. The myriapods show a transition from the skin-respiration of the leech and earth-worm to the air-tubes of the insect. The latter possesses the most peculiar and effective system for aeration. As in the annelids a complex system of tubes conveys water to the tissues, so in the insects all parts of the body, and the nutritive fluid, are bathed by air admitted through a complex tube-system. So complete is the aeration of the whole structure, that practically the blood of an ”

“ Species mihi ignota.
Variegated with ferruginous; head large, subquadrate, polished, elevated, and thickened at its posterior margin; antennæ short, pubescent; ocelli on each side 23; labium polished, with scattered hairs; dental lamina lunate, anterior external angles elongate, profoundly emarginate; denticules 14 acute, black; dorsal scuta complanate rugose, their margins elevated; feet bare, with small articular spines. Species unknown to me.
L. planus, Newport, Linn. Trans, xix, p. 366; Catalogue of British Museum (Myriapoda) , p. 18.
"⁠"⁠P. Gervais, Apt. iv, p. 236; et Tabl. ”

“ I have therefore divided the Diplopoda into two suborders, the Chilognatha and Sugentia, retaining old names, but giving new significance to them. The minor characters have seemed to me to confirm this, and to indicate that it is coincident with the plan on which the Myriapoda have been created. M. Brandt (Recueil, p. 26) divides the Chilopoda into the Schizotarsia and Holotarsia. ”

“ HABITS–CLASSIFICATION–STRUCTURE–CHILOGNATHA–CHILOPODA–SCHIZOTARSIA–SYMPHYLA–PAUROPODA–EMBRYOLOGY–PALAEONTOLOGY.
Tracheata with separated head and numerous, fairly similar segments. They have one pair of antennae, two or three pairs of mouth appendages, and numerous pairs of legs.
The Myriapoda are a class of animals which are widely distributed, and are represented in almost every part of the globe. Heat and cold alike seem to offer favourable conditions for their existence, and they flourish both in the most fertile and the most barren countries. ”

“ All the myriapods found in the woods and fields feed upon decaying vegetation, such as leaves, stems of weeds, and rotten wood, and in winter three or four species can usually be found within or beneath every decaying log or stump. One species with very long legs, Scutigera forceps (Raf.) , is often found in damp houses or in cellars. ”

“ The Schizotarsia, the third Order, also have seven pairs of legs when hatched.
The legs make their appearance not one by one but in batches (in Julus terrestris in batches of five) . The addition of legs and segments to the body takes place, not at the end of the body, but between the end segment and the penultimate.
This is a short sketch of the gradual development of the Myriapoda from the ovum to the fully-grown animal. ”

“ Before leaving for Madeira, Metchnikoff had obtained a scientific mission and a subsidy from the Society of Natural Science Lovers of Moscow, and felt it a moral obligation to obtain some results. The scantiness of the marine fauna was a bitter disappointment; he had to fall back upon what little he found, and embarked on the study, hitherto unknown, of the embryology of Myriapoda. ”