THE VOYAGE OF H.M.S. CHALLENGER. 



Class Crustacea, sub-class Entomostraca, order Gnathostomata, legion Lophyropoda, 



tribe Ostracoda. 



H 

 < 

 O 



Simple, subpediform, geniculate, 

 clawed at tlie apex, not very 

 unlike the anterior antennjie ; 

 both paii-s either bearing long 

 setaa and adapted for swim- 

 ming, or shortly setose and not 

 used for s-\vimming. Mandi- 

 bles distinct, mostly strongly 

 toothed at the lower extremity ; 

 palp of moderate size, and bear- 

 ing a more or less developed 

 branchial appendage. First 

 pair of maxillte bearing a 

 large branchial plate. Feet. 



' One branch rudimentary, 

 immobile ; the other elon- 

 gated, cylindrical, flexible, 

 many-jointed, armed with 

 long natatory sette ar- 

 ranged in a single series ; 

 basal portion very large 

 and stout, filled with mus- 

 cular bands. Anterior an- 

 tennre scarcely natatory. 

 Mandible-palp very large, 

 geniculate, subpediform, 

 destitute of a branchial 

 appendage. First pair- of 

 jaws without a branchial 

 plate. Postabdomen di- 

 vided into two broad 

 plates, which are ungui- 

 ferous behind. Feet. 



Two pairs, the last pair bent up within 

 the valves. Postabdomen usually 

 forming two elongated narrow rami, 

 which are usually clawed at the apex. 



Cyprid^. 



Two pairs, both ambulatory and nearly ~] 



alike in structure. Postabdomen 1 „ 



, . , r ■ , „ f" Darwinellid^. 



rudmientary, torming two small I 



conical processes. -^ 



Three pairs, all ambulatory, much alike 1 

 in struotm'e, and directed forwards. I 

 Postabdomen rudimentary, forming r CytheriDjE. 

 two very small lobes. Antennse very 

 little adapted for swimming. 



One pair only, of singular shape, form- ~ 

 ing an elongated, curved, flexible, 

 annulated, vermiform appendage, 

 which is spiniferous towards the 

 apex. Anterior antennse large, dis- 

 tinctly jointed, geniculate at the 

 base. Mandibles proper obsolete. 

 Second pair of jaws bearing a large 

 branchial plate. Eyes comijound, 

 pedunculated, widely separated ; be- 

 tween the two in front a large simple 

 eye and a short, frontal tentacle. 



Two paii'S, the posterior very small and 

 rudimentary ; the anterior jirovided, 

 like the second pair of jaws, with a 

 small, lobed branchial plate. An- 

 terior antennaa of the female small 

 and weak, immobile, and indistinctly 

 jointed. Mandibles distinct. No 

 eyes. Frontal tentacle very large, 

 I, and mostly dilated at the apex. 



PODOCOPA. 



Cypridinid^. 



CONCH^CIAD^. 



I MYODOCOPA. 



Both branches well developed, movable, and natatory. Aiterior an- 

 tennse also natatory, not geniculated, ending in a lash of long sette. 

 Mandibles distinct; palp short and scarcely pediform, provided 

 with a small branchial appendage. Two pairs only of thoracic J" Polycopid^e. 

 appendages ; the anterior large, bifid, natatory ; the posterior 

 membranaceous and branchial. Eyes wanting. Postabdomen 

 divided into two short laminse, spinous behind. 



Flattened, similar to the feet of the Cope'poda, basal portion bi-articu- ~ 

 late and geniculated; branches flattened, composed of few joints, 

 and bearing numerous setfe on both margins. Anterior antenna 

 very large and strong, many -jointed, geniculated at the base, shortly 

 spiniferous. Mandil^les small and weak, palps large. Three pairs 

 only of thoracic appendages, all niaxilliform. Palp of mandible j> Cytherellid/E. 

 and first maxilla bearing on the inner side a comb of large set;e. 

 First and second pairs of maxillae provided with a large branchial 

 plate; third pair rudimentary in the female, in the male well 

 developed and prehensile. Postabdominal rami small and narrow, 

 distinctly separated, and spiniferous at the apex. 



CLADOCOPA. 



PLATYCOPA. 



