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Show . 132 CRUST AU:&A • cena, Swamm., Bib. Nat., xxxi; Perroquet d'eau, Geoff., aist. Ins. II, 455; Schref., Die Gri.in., arm., Polyp., 17551 I, 1, 8; Straus, Mem. du Mus. d'Hist. Nat. V, xxix, 1-20; Jurine, Mon., Yiii-xi. According to Straus, this species has a large convex rostrum; setre of the oars plumose; first tubercle of the sixth segment linguiform; inferior edge of the valves dentated; valves terminated by a short tail, which is obtuse in the females. This last characte1· distinguishes it from another species with which it has been confounded, the Daph. longispina, Str. Deg. Insect. VII, xxvii, 1-4. The female is four millimetres in leugth(l ). The last subgenus of the Lophyropa is LYNoEus, Mi.ill.-Chilodorus, Leach. It cart scarcely be distinguished from the preceding except by the oars, evidently shorter than the shell, the inferior portion of which has but little or no projection. According to Straus the articula· tions of the branchire are more numerous than in the preceding subgenera. They all have a little spot before their eye which has the appearance of a second one. The rostrum, longer in proportion than that of the Daphnire, is curved and pointed(2). The second section of the Branchiopoda, that of the PHYLLOPA, is distinguished from the first, as already stated, by the number of feet, which at least amounts to twenty(3) and by the lamellated or foliaceous form of their joints. There are always two eyes, which are sometimes pediculated: several of them have also an ocellus. They form two principal groups. In the first-CEnATOPTHALMA, Lat.-there are never less than ten pairs of feet, nor more than twenty-two; the vesicular body at their base is wanting; the anterior are never much longer than the others, nor ramified. The body is contained in a shell resembling thatofa bivalve, or is naked, each thoracic segment bearing a pair of ex· posed feet. The eyes arc sometimes sessile, small and closely ap· proximated; at others, and most frequently, they are situated at the extremity of two movable pedicles. The ova are internal or external, and are contained in a sac at the base of the tail. .(1) For the other gpecies, see Mem. cit. of Straus; MUll., Entom., and Jurine, Hlst: d~s Mon. fam. II, p. 185-58, and p. 181, 200. For the D. tima, and D. longt.apma, see Rand., Monc. V-VII. (2~ See MUll., Entom., G. lyncew1 Jurine, Monoc. p. 151, 158; and Desmar., Cons1d., 375-378. (3) These animal• repreaent among the CrustaeeA, the Myriapoda of the cla11 oflnse.cb. BRANCHIOPODA. · 133 h eyes are sessile and immovableJ the body is invested with ·Here t e . l h 11 resembling that of a molluscous btvalve, and the ova: JD ova s e . always internal. Such is the r1es are LIMNADIA, Ad. Brong.(l) The Limnadire are so closely allied to the preceding s.ubgenus, h ly species known was placed among the Daphmre by the that t eon . Hermann The shell is bivalve, oval, and meioses the body, younger • l' d I h h d d which is elongated, linear, and inflected torwar s. n t e ea , an. almost confounded with it, we find: 1, two eyes closely a~pro:x1- t d and placed transversely; 2, four antennre, two of whtch are maeh the largest, each composed of a pedunc1 e o f e·t gh t J· O·m ts an d mfu ctw o setaceous branches or threads d1. v1' d e d .m to e.t gh t segmen t s 0 an d so mewhat silky'· the two others are intermediate, small, sim. p. le, and widened at base; 3, the mouth, situated beneath, and. con~tstmg f two inflated mandibles arcuated and truncated at the mfertor ex,01 mity and of two foliaceous jaws. These parts when united form ar es ort o'f inferior rostrum. The body, properly so calle d , 1· s d1' v1'd e d into twenty-three segments, each of which, except the last, bears a pair of bt•anchial feet. All the.s~ f~et ~re ?imilar, stron.g!y compressed and bifid; their external dlvlston 1s stmple, and c1hated on the ex;erioredge; the other has four joints, and is strongly ciliated along its interior margin. The first twelve pairs are of equal length, and larger than the others; the length of the latte_r progressively diminishes. The eleventh pair, and the two followmg ones, have a slender thread at their base, which ascends into the cavity situated between the back and the shell, in order to support the ova. The last segment on the tail is terminated by two threads. The ovaries are internal, and placed along the sides of the intestinal canal, extending from the base of the first pair of feet to the eighteenth; their openings appear to be at the root of some of those that are intermedia~e: The eggs, after having been produced, occupy the dorsal cav1ty above mentioned, and are secured there by means of small threads, which adhere to those of the feet. At first they are round and transparent; they afterwards assume a yellowish tint, which is subsequently darker towards the centre, and their figure becomes irregular and angular. All the individuals examined by M. Ad. Brongniart were provided with them. The males, allowing the sex to exist, do not appear at (1) In my work on the natural families of the animal kingdom, this subgenus, with that of .!lptut, composes my family of the Aspidiphora; it approximates to this one in the number of feet, and to the Daphniz in the shell. |