RECENT BRITISH OSTRACODA. 



359 



The following synopsis of the sections and families here described is given by 

 Sars : — 



-1^ 

 p 

 o 

 o 



< 

 o 



'simple, subpediform, geniculate, clawed 

 at the apex, not very unlike the upper 

 antennae. Both pairs of antennae either 

 bearing long setre and adapted for swim- 

 ming, or shortly setose and not used for 

 swimming. Mandibles distinct, mostly 

 strongly toothed at the lower extremity ; 

 palp of moderate size, and bearing a more 

 or less developed bi-anchial appendage. 

 First pair of maxillae bearing a large 

 branchial plate. Feet 



one branch rudimentary, immo- 

 bile ; the other elongated, cylindrical, 

 flexible, many-jointed, armed with 

 long natatory setae, arranged in a 

 single series ; basal portion very large 

 and stout, filled with muscular bands. 

 Upper antennae scarcely natatory. 

 Mandibular palp very large, genicu- 

 late, subpediform, destitute of a bran- 

 chial appendage. First pair of jaws 

 without a branchial plate. Post- 

 abdomen divided into two broad 

 plates, which are imguiferous behind. 

 Feet 



two pairs, the last bent up within the"] 

 valves. Postabdomen forming two elon- [ Qypridje 

 gated narrow rami, wliicli are usually 

 clawed at the apex. 



[>three pairs, all ambulatory, much alike 

 in structure, and directed forwards. Post- 

 abdomen rudimentary, forming two veiy !> 

 small lobes. Antennae very little adapted 

 for swimming. 



PODOCOPA. 



Cythe- 



''one pair only, of singular shape, forming"| 

 an elongated, curved, flexible, annulated, 

 vermiform appendage, which is spiniferous 

 towards the apex. Upper antennte large, 

 distinctly jointed, geniculate at the base. Cypeidi 

 Mandibles proper obsolete. Second pair 

 of jaws bearing a large branchial plate. 

 E3'es compound, pedunculated, ■widely 

 separated ; between the two in front a 

 large simple eye and a short fi'ontal ten- 

 tacle. J 



two pairs, the posterior very small and" 

 rudimentary; the anterior provided, like 

 the second pair of jaws, with a small, 

 lobed branchial plate. Upper antennte of Conchce- 

 the female small and weak, immobile and 

 indistinctly jointed. Mandibles distinct. 

 No eyes. Frontal tentacle very large, and 



.MYODUCOPA. 



mostly dilated at the apex. 



both branches well developed, moveable, and natatory. Upper antennae also"] 

 natatory, not geniculate, ending iu a lash of long setfe. Mandibles distinct, palp | 

 short and scarcely pediform, provided ■with a small branchial appendage. Two [ 

 pairs only of thoracic appendages ; the anterior large, bifid, natatory ; the poste- ( 

 rior membranaceous and branchial. Eyes wanting. Postabdomen divided into | 

 two short laminae, spinous behind. J 



flattened, similar to the feet of the Copepoda, basal portion biarticidate and 

 geniculate; branches flattened, composed of few joints, and bearing numerous 

 setae on both margins. Upper antennEe very large and strong, many-jointed, 

 geniculate at the base, shortly spiniferous. Mandibles small and weak, palp large. 

 Three pairs only of thoracic appendages, all maxilliform. Palp of the mandible J> 

 and first jaw bearing internally a comb of large setas. First and second pairs of 

 jaws provided with a large branchial plate; third pair rudimentary in the female, 

 in the male well developed and prehensile, Postabdominal rami small and 

 nan'ow, distinctly separated, and spiniferous at the apex. 



POLYCO- 



CLADOCOPA. 



Cythe- ( PLATYCOPA. 



EELLID^J. 



Section I. PODOCOPA. 

 Pam. 1. CypRiDiE, 



Valves mostly thin and smooth, more or less sinuated below. Upper antenna? mostly 

 seven-jointed, and beset with numerous setse, which form a dense brush of greater or less 

 length; lower antennse geniculate and bent backwards, four- or five-jointed, armed at the 

 distal extremity with from three to five long, slightly curved claws, and bearing commonly 

 on the posterior aspect of the antepenultimate joint a bundle of setse. Mandibles 

 powerful, and divided at the extremity into several teeth, bearing a large four-jointed 

 palp, the first joint of which is provided with a branchial appendage. Two pairs of jaws : 

 the first large, and divided into four digital segments, the anterior segment being 

 larger than the rest, two-jointed and giving attachment to a large branchial plate : 



