BRANCHIOPODA. ! 1.3 



gradually pointed, and immediately behind them is a terminal, nearly semiglobular joint, replacing a tail, and 

 winch is furnished with an elongated filament, probably an oviduct. I have observed near the middle of the 

 fifth and four following pairs of feet a globose body, probably analogous to the vesicles which these organs present 

 in J juts. The only apecies,E. al/>itt«, Latr., is very small, and of a whitish colour. It is found in the River of ' 



2. The Aspidiphora, Latr., [or second principal group of the Phyllopodous Branchiopoda~\ have sixty 

 pairs of legs, all of which are furnished on the outside, near the base, with a large oval vesicle, and of 

 which the two anterior, much larger than the rest, and ramose, resemble antennas. A large shell covers 

 the major part of the upper side of the body, almost entirely disengaged, (shield-like,) posteriorly cniar- 

 ginate, and bearing anteriorly, in a confined space, three simple sessile eyes, of which the two anterior 

 are larger and lunular ; and two bivalve capsules containing the eggs, annexed to the eleventh pair of 

 feet. Such are the characters of the genus 



Aptu, Scop., (forming part of the genus Jiinoculus, GeoftVoy, and Limiilu t, Mull.). — The body, including the 

 shell, is oval, broader, and rounded in front, and narrowed behind, forming a tail ; but if we remove the shell, it is 

 nearly cylindrical, convex above, concave and divided by a longitudinal canal beneath, terninating in an elongated 

 cone. Itis composed of thirty joints, equally diminishing in size towards the posterior extremity, and which, 

 with the exception of the seven or eight terminal ones, bear the feet. The ten anterior segments are membrai 

 soft, and without spines, presenting on each side a small eminence, or knob, with only a single pair of legs to 

 each. The others are more solid and horny, with a row of small spines on the outer edge : the last is longer than 

 the preceding, nearly square, depressed, angular, and terminated by two filaments, or articulated setae. In BOme 

 species, composing the genus Lepidurus, Leach, there is a corneous elliptic plate. If the number of legs be one 

 hundred and twenty, the terminal segments after the eleventh and twelfth must severally bear more than a pair of 

 legs, (in which respect these animals approach the Myriapoda). The shell, perfectly disengaged beyond its an- 

 terior attachment, covers the greater part of the body, and thus defends the anterior segments, which are of a 

 softer consistence than the others ; it consists of a large, corneous scale, very slender, nearly diaphanous, exhibit- 

 ing the superior teguments of the head and thorax united, and funning alarge,oval shield, deeply incised at its 

 posterior extremity. Its upper surface is divided by a transverse line, forming two united arcs, into twos 

 the anteriorof a semilunar form, corresponding with the head, and the other with the thorax. The anterior is fur- 

 nished with the three eyes, and the posterior is carinated down the middle. The shell is only fixed to the body at its 

 anterior extremity, so that the bark of the animal may in- distinctly seen throughout its whole length. Immedi- 

 ately beneath the frontal disc are placed the antennae and mouth. The antenna; are two in number, inserted on 

 each side of the mandibles, very Bhort, filiform, and composed of two equal joints. The mouth consists of a square 

 labium ; two strong, corneous mandibles, destitute of palpi, and toothed at the tip; a tongue, deeply notched ; two 

 pairs of foliacenus maxilla , the superior spirjed, and ciliated on the inner edge, and the inferior resembling small 

 false legs. They are terminated by a slender, elongated joint, prolonged externally at their base into an ear- 

 shaped appendage, and bearing a kind of palpus. The legs, about one hundred and twenty in number, gradually 

 diminish in size after the Becond pair; they are all compressed, foliaceous, and composed of three joints, not 

 including the two long filaments at the tip of the two anterior, and the two leaflets terminating the following, 

 which may be regarded as the analogues of a claw, having the two lingers elongated, and converted Into antl nn l - 

 like filaments ; upon the posterior edge of this joint is inserted a large branchial membrane, and the follow in::, or 

 the second, also bears on the same side an oval, vesicular, red sac. The opposite edge of these legs also exhibits 

 four triangular, ciliated leaflets. The eleventh pair of legs is very remarkable ; the first joint exhibits, behind 

 the vesicle, two circular valves, applied upon each other, formed of two plates, and inclosing tl which re- 



semble small, red grains. All the indiv iduals hitherto examined have exhibited this structure, and it lias, there- 

 fore, been supposed that each has the power of fecundating its ovv ii eggs, and that there are DO males. 



These Crustai ea inhabit ditches, iai.es, and standing waters, generally iii Innumerable quantities. Raised thence 

 by violent hurricanes into the air, they have been observed to fall like rain. The) i rail] found in spring 



and the beginning of summer. Their food principally consists of young Tadpoles. Thej swim well on tin- back, 



and when they burrow into the land, tin, elevate their tails in the water. When lirst hatched they have only one 



eye, four legs, like oars or arms, with whorls of hain ; the second pair being the largest. The bod] has no tail, 

 and the shell (mis covers the front half of the body. The other organs aregraduall] developed during the succeeding 

 iiioi.kings. 



The species being fe* in number, it is ool necessary to form (as Leach has done) with th 

 which hasea plate between the tails, a distinct geuus (Lepidunu, Leach), type, Monoeulmaput l 

 Linn. The ridge of the shield terminates In a small spine posteriorly, which is not the case in 

 Apii mix [IAmuliu pakuirit, (lull.), which latter is also destitute of a plate between the 



tail, 'i ins forms the type of the restricted genus Aputat Leach, wl jjured another 



lea, ./. MomtaguL 

 ' Protopittowia, Lstreille, In Nouv. Mt m. du ISuu ton, is composed ofa tninnl Mada- 



ar, exactly resembling a species of Gyrinus in its external appearance. It isfigui rin, 



/. tograpkie Crtut., pi, rypterui, Dekay, is composed of aver] remarkable fossil animal, 



allied to Aptu and other analogous genera, the beadnol being distinct from the bods, which is 

 oval, but attenuated behind, with two large dorsal eyes, and four pans of legs, the fourth being 

 verj lai je, and like broad o irs. dnnali Nat. Hut., \evs x 01 k, 1835, p, 37 •■ ; 



