Cirri

“ In Ibla, the males are attached low down within the sack of the female; they may be said to consist of a mouth surmounted on a long peduncle, for there is no capitulum or general covering, and the whole thorax is in a rudimentary condition, the cirri being reduced to two distorted pairs. As these males certainly moult several times and grow a little, they must feed; and as they have no cirri fit for action, they must seize their food by the contortions of their peduncle, which we know homologically consists of the three first segments of the head. ”

“ In some specimens the radii extended down close to the basal cup, and only very minute clefts were left between the opposed edges of the parietes.
In the animal’s body the only noticeable character was, that on the anterior ramus of the fourth pair of cirri, some of the segments were furnished with very broad and thick, small, downwardly curved, teeth or hooks, like those described in certain varieties of A. sulcata; but they are here stronger and thicker. ”

“ Cirri.—The five posterior pair are elongated, very little curled, with short pedicels; their segments are long, not at all protuberant in front, bearing five or six pairs of long, slightly serrated spines, with a very minute tuft of bristles between each pair, and with some short lateral spines on the inner side of each segment; on the fourth pair of cirri, these lateral spines are considerably developed; dorsal tufts consist of fine spines, with one much longer than the others. ”

“ The well-articulated thorax, by the aid of the muscles attached to every segment, can certainly be doubled up and contracted, [Pg 577] so that the cirri with their pedicels (coloured purple like the exposed labrum) can be wholly protruded out of the sack and shell-cavity. The three cirri no doubt can be separated a little from each other, both transversely and longitudinally; and according to analogy, the two rami of each cirrus can likewise be separated: there are, also, muscles for moving the two segments of the pedicel of each cirrus; and other muscles run up the many segments of the rami. ”

“ Five of these are inserted on the right aide in a deep in-sinking, and the other 2 in a similar depression on the left ventral surface. Above the 5 right-side cirri, i.e., dorsal to them, but in the same depression, are 3 angular cirri. A few edge cirri are found to the left of them and another to the right of the 5 cirri. The contractile vacuole is on the left side between the main groups of cirri. The macronucleus is band-form or spherical, and is situated in the middle region of the body. Movement consists in forward swimming with sudden springs. ”

“ Syllis.—The tentacles and cirri are moniliform; the palps large; there is a single dorsal tooth, which is provided with a poison gland, the duct of which opens near its apex; it is used rather for stabbing its prey than for grasping and tearing. S. krohnii Ehlers, is abundant under stones, and forms tubes of sand; it is nearly an inch long, and consists of some eighty-five to ninety-five segments marked with yellow bands. It may readily be identified by longer dorsal cirri, terminally dilated, alternating with shorter ones. ”

“ In Ibla, the thorax is reduced to a mere flap, and only two pairs of cirri exist in a most useless and rudimentary state, but there is a well organised mouth, stomach, and anus. In the males of Scalpellum vulgare, ornatum, and rutilum there is no mouth or stomach, but there is a thorax with four pairs of minute, modified cirri, and a large abdominal lobe. Here, in the male Alcippe, all these negatives are united, we have no mouth, no stomach, no thorax, no cirri, no abdomen! The archetype crustacean consists of twenty-one segments ”

“ Tentacular cirri much longer than the tentacles, attenuated distad, pointed. The notocirri are all similarly attenuated and run out to a rather fine point. Neurocirri very thick, conical, each with a black dot near middle. Contrasting with the preceding species in color in having the dorsum in general light, fulvous, in part slightly dusky, with a series of dark, blackish, transverse lines across dorsum, there being four somites between each two dark lines. The body is narrowed toward both ends; venter flat and dorsum [10] strongly arched; hesioniform. ”

“ Two well developed cirri and two rudimentary ones are present in Apus, and they are also to be found in other phyllopods and some isopods. It is, however, characteristic of the Crustacea as a whole to lack appendages on the anal segment. Caudal cirri (cerci) are much more freely developed in the hexapods than in the Crustacea, particularly in the more primitive orders, Palæodictyoptera, Apterygota, Archiptera, and Neuroptera. They are supposed, in this case, to be modified limbs, and therefore not homologous with the bristles on the anal segment of an annelid. ”

“ The peristomium, which extends forwards on each side {322}of the prostomium, bears a pair of very long cirri (usually termed "tentacles") normally directed backwards, very mobile, and more or less coiled. They are readily thrown off by the animal. The notopodial cirri are long, finger-shaped, and curved over the back; they are vascular and ciliated, and function as "gills." The neuropodia project laterally. Both are usually provided with a "podal membrane" along their outer margin. There are no ventral cirri; the dorsal chaetae are fringed capillaries; the ventral are "crotchets." ”

“ This species is very common in the Woods Hole waters. It is small, colorless, and very active. The most characteristic feature is the posterior end with its relatively enormous cirri, which are apparently large enough for an animal four times its size. The form is ovoid, widened posteriorly.
The ventral surface is flat and has two excavations in the posterior end. The right hollow is larger and contains 5 great cirri of unequal size, the extreme right one being the largest. The left hollow contains 2 cirri, also of dissimilar size. ”

“ Atlantic and Mediterranean. In Psammolyce the elytra are covered with sand grains. British and Mediterranean.
Fam. 4. Phyllodocidae.—The members of this family make use of the foliaceous cirri (Fig. 136, F) in their very active movements. The rounded prostomium bears four or five tentacles; there are four long peristomial cirri on each side (see Fig. 134, E) .
Sub-Fam. 1. Phyllodocina.—The body is elongated, with numerous segments; the eyes are small; the chaetae are jointed; the dorsal and ventral cirri are foliaceous; the pharynx is covered with papillae externally, but contains no "jaws." ”

“ The chief features by which this species is distinguished from the frequently described M. pulex of Europe are the number of anterior cirri and the ring of true cilia in place of the central girdle of cirri. The European form is described with four anterior bristles; the present form has from 28 to 32. The radial cilia differ decidedly from the more powerful cirri and they are not in one plane, so that counting is difficult; they are not closely set. The presence of tentacles makes these forms of especial theoretical interest, especially in the light of the origin of Suctoria. ”

“ Mouth.—The crest of the labrum is toothed: the palpi are short, truncated, with long spines arising from their ends, and along the basal exterior margin. In the mandibles the first tooth is seated rather far from the succeeding teeth: the inferior part is coarsely pectinated: the maxillæ are deeply notched. The tips of second pair of Cirri have many coarsely pectinated spines: the shorter ramus had six segments, whilst the shorter ramus of the third pair had eighteen segments: the segments on the posterior cirri carry five pairs of main spines. ”

“ The outer maxillæ (like those at Pl. X, fig. 16) , are internally clothed continuously with spines. The olfactory orifices are not at all prominent.
Cirri.—The first pair is placed near the second pair, and is of considerable length; the second has the anterior ramus thicker than the posterior ramus, and the segments brush-like; the segments (Pl. X, fig. 26) of the four posterior cirri bear from four to six pair of long spines, with a row of small intermediate spines: in the posterior cirri of L. australis the lateral rim spines are much developed ”

“ I took home some specimens, and placing them in perfectly fresh water they continued for many hours expanding and retracting their cirri with perfect regularity and vigour. Here then we [Pg 253] have a Balanus capable of living in fresh water, and likewise in the saltest seas: even brackish water is a deadly poison to several, probably to most, species of the genus; but this, as we have seen, is not the case with the allied B. eburneus. The water, I may add, at Woolwich, on the Thames, whence I have received B. improvisus, must at times be very brackish. ”

“ Aspidisca hexeris Quennerstedt '67. Fig. 56.
The carapace is elliptical, about 1-1/2 times as long as broad, rounded at the extremities. The left border of the carapace bears a spur-like projection. The ventral cirri are short and thick, and are very characteristic of the species. When moving slowly they look much like nicely-pointed paint brushes, but when the animal is compressed they quickly become fibrillated, and then look like extremely old and worn brushes. These cirri are placed in depressions in the ventral surface and each one appears to come from a specific shoulder. ”

“ Cirri.—First pair lost. The arrangement of the spines on all is most abnormal, Pl. X, fig. 29: dorsal tuft long, arranged in a transverse line and seated in a deep notch; in the sixth cirrus, the spines on the lower segments are fine, those on the upper segments are thick and claw-like, mingled with some fine spines; in the four anterior cirri the spines of the dorsal tufts are even thicker and more claw-like. On the anterior faces, also, of all the segments the spines form a single row; they are shorter than those composing the dorsal tuft ”

“ The crest close over the [Pg 41] supra-œsophageal cavity, is generally furnished with small, often bead-like teeth. The Palpi are small, their apices never actually touching each other; they are more or less blunt, not differing much in shape in the different genera (Pl. X, figs. 6 to 8) , and clothed with spines. They are not capable of movement; their function seems to be to prevent prey, brought by the cirri, escaping over the labrum; I infer this from finding in Anelasma and in the male of Ibla, which have the cirri functionless, that the palpi are rudimentary. ”

“ Tentacular cirri of same form as tentacles but longer. Neurocirri thick, short, distally rounded. Natocirri long, filiform, tapering distad, weakly ringed; showing a tendency to alternate in height on the sides of the body, the first being notably farther distad than the second, the third than the second and fourth, etc. Setae numerous; the appendage short, falcate, with tip simple, but a slender tooth near middle of curved edge. Segments short, crowded, near one hundred in number.
Length of type, 21 mm.; greatest width, 2.2 mm. ”

“ Although in the dead state, the aperture of the capitulum seems to be always gaping, yet I have little doubt, that the living animal can fold the flexible membrane, like a mantle, round its thorax and cirri, and thus protect, though feebly compared with most Cirripedes, these organs. I suspect that the mouth is always exposed. ”

“ The movements of the peduncle must, also, supply those of the probosciformed penis, almost invariably present with other Cirripedes, but here absent. If compelled to class these males without regard to the female, great difficulty would be experienced; we could hardly place in the family of the Lepadidæ, a Cirripede without a capitulum, and without cirri, those very organs which give their name to the class, and with a thorax reduced to the dimensions of a lower lip ”

“ The male Ibla must seize its prey, guided probably by its well-developed olfactory organs, through the movement of its long, flexible body, furnished with muscles, and with the mouth seated on the summit. We have already seen one instance of a Cirripede, the Anelasma, obtaining its food without the aid of cirri, by means of its probosciformed, flexible mouth. The eye can serve only to announce to the male when the female opens her valves, allowing occasionally some minute prey to enter. ”

“ A peculiar modification is found in the trunk-limbs of the Cirripedia (fig. 9) , in which both rami are multiarticulate and filiform and fringed with long bristles. When protruded from the opening of the shell these “cirri” are spread out to form a casting-net for the capture of minute floating prey.
Gills or branchiae may be developed by parts of an appendage becoming thin-walled and vascular and either expanded into a thin lamella or ramified. ”

“ The cirripedia are so called from the cirri or arms which they possess, and by which they are enabled to entangle or catch their food, as in a net. They hold themselves by a “foot stalk.” The goose-mussel, or barnacle, is very common, but must not be confounded with the limpet. ”

“ And lastly, I have seen specimens from Ayrshire, with the parietes permeated by regular tubes, but with the tergum in an intermediate condition, and with the segments of the posterior cirri not more numerous or more elongated than in B. balanoides, supporting only six or seven pairs of spines, that is only one more than is common with B. balanoides; so that it was impossible to decide whether to rank the Ayrshire [Pg 271] specimen under var. (a) or under the common form, so that I was compelled to give up var. (a) as a species. ”