File:The animal kingdom - arranged after its organization; forming a natural history of animals, and an introduction to comparative anatomy (1863) (18010219118).jpg

Title: The animal kingdom : arranged after its organization; forming a natural history of animals, and an introduction to comparative anatomy
Identifier: animalkingdomarr00cuviuoft (find matches)
Year: 1863 (1860s)
Authors: Cuvier, Georges, baron, 1769-1832; Carpenter, William Benjamin, 1813-1885; Westwood, J. O. (John Obadiah), 1805-1893
Subjects: Zoology
Publisher: London H. G. Bohn
Contributing Library: Gerstein - University of Toronto
Digitizing Sponsor: MSN

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444. Div. 3. ARTICULATA.—CRUSTACEA. Class 1. THE SECOND ORDER OF ENTOMOSTRACA,— (T/ie Seventh and last of the Class Crustacea),— PCECILOPODA,— Is distinguished from the preceding by the diversity in the form of the feet, of which the anterior, of an indeterminate number, are ambulatory, or fitted for pre- hension, and the others, lamelliforra or pinnated, are branchial, and fitted for swim- ming. But it is especially in the absence of mandibles and maxillae of the ordinary form that they are separated from all the other Crustacea ; sometimes these organs are replaced by the basal joint of the six anterior legs being armed with numerous minute spines ; sometimes the organs of manducation consist either in an external siphon in the form of an inarticulated beak, or in some other instrument fit for suction, but hidden, or very indistinct. The body is nearly always covered, either entirely or for the most part, by a shell in the shape of a shield, composed of a single piece in the majority, but of two parts in some, and always exhibiting two eyes at least when these organs are distinct. Two of the antennae (Chelicerce, Latr.) are in many in form of hooks, and i)erform the functions as such. The number of their legs is twelve in the greater number*, and of ten or twenty-two in nearly all the others. They reside for the most part upon aquatic animals, and most commonly on fishes. We divide this Order into two families, (Xyphosura and Siphonostoma,) which, in my Families Naturelles, composed two separate orders. THE FIRST FAMILY OF PCECILOPODA,— Xyphosura,— Is distinguished from the following hy many characters : they have no siphon ; the coxae of the six pairs of fore-lpgs are hcset with minute teeth, and perform the office of jaws ; the number of legs is twenty- two ; the ten anterior, with the exception of the two anterior in the males, are terminated hy a two- fingered claw, and inserted, as well as the two following, beneath a large semilunar shield ; the latter bear the organs of generation, and are in the form of large leaves, as well as the ten following, which arc l)ranchial, and annexed to the nnder side of a second shield, which is terminated by a very powerful, horny, moveable style, like a sword. These animals are wanderers. They compose the genus Limultu, Fab., of which the species have received the name of (King^ Crabs), or crabs of the Moluccas. The ■early rounded body, somewhat elon^^ated and narrowed behind, is divided into two parts, and covered by a solid shell of two pieces, one for each division of the body ; it is very concave beneath, and exhibits on its upper side two longitudinal impressions, one on each side, and a central dorsal ridge. The fore part of the shell, or that which covers the front of the body, is much larger than the other, and forms a larje semilunar shield, having on its upper side two oval eyes, with very nuniernus facets, in the form of minute grains, and situated one on each side on the outside of the longitudinal ridge ; and at the anterior extremity of that of the centre, which extends to the pieces of the shell, are two small, simple eyes, close together. Within the cavity of the anterior shell is a small swollen labrum, ridged in the centre, terminated in a point, and above which are inserted two small antenna?, in tlie form of small didactyle claws, and elbowed in the middle of their length, at the union of the fir.st and following joint. Immediately beneath are inserted, close together in pairs, in two lines, twelve legs, of which the ten anterior (the two or four anterior in the males only excepted) are terminated by a didactyle claw, and of which the basal joint is tig. 23.—Liniuius advanced interiorly into a lobe armed with numerous minute spines, and performs the functions poyp emus. of the maxillae, lliese legs progressively increase m size, and, with the exception of the fifth pair, arc composed of six joints, including the moveable finger of the claw; the fifth pair have an additional jomt, and also a curved appendage at the base, directed backwards, and composed of two joints; their fifth * Fourteen in some species, arcordiiifif to Leach; but the pair which fcrior anteniiK. The Arjfuli, which, in respect to tlicir locomotive he considers to be the anterior pair, appears to me to be the two in- I ori^nnH, are the most perfect, have only twelve legs.
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