ENTOMOSTRACA. 



[ 288 ] 



EXTOMOSTRACA. 



beris (CyprideUa, Cyprella, Entomis ?, 

 fossil). 



Fam. 4. ENTOMOCONCHIB^E. 



Gen. : Heterodesmus, Entomoconchus. 



Fam. 6. CONCHCECIID^. Feet 2 pairs, 

 posterior rudimentary; mandibles di- 

 stinct j eyes none. 

 Gen. : Conchcecia, Halocypris. 



Sect. 3. CLADOCOPA. Inferior antennae 

 2-branched, both branches well deve- 

 loped, natatory ; upper antennae nata- 

 tory, not geniculate, with a lash of long 

 setae ; mandibles distinct, palp short ; 

 2 pairs of thoracic appendages ante- 

 rior large, natatory, posterior membra- 

 naceous and branchial. 



Fam. 6. POLYCOPIDJE. Char. Those of 



the section. 

 Gen. : Poly cope. 



Sect. 4. PLATYCOPA. Lower antennae 2- 

 branched, flattened ; branches few- 

 jointed, with numerous setae. Supe- 

 rior antennae strong, geniculate, shortly 

 spiniferous ; mandibles small, palp 

 large ; 3 pairs of thoracic append- 

 ages, all maxilliform ; first and second 

 pairs of jaws with a large branchial 

 plate. 



Fam. 7. CYTHERELLIDJE. 

 Gen. Cytherella. 



Order 2. Copepoda. Shell jointed, forming 

 a buckler, enclosing the head and thorax ; 

 legs five pairs, mostly adapted for swim- 

 ming ; ovary external. 



Fam. 1. CYCLOPID^:. Head consolidated 

 with the thorax; foot-jaws two pairs, 

 generally small ; fifth pair of legs rudi- 

 mentary ; eye single ; both superior 

 (larger) antennae in the male furnished 

 with a swollen hinge joint. 



Cyclops. Foot-jaws large and strong, 

 branched ; ovaries double (PI. 20. figs. 

 8,9). 



Canthocamptus. Foot-jaws small, sim- 

 ple ; ovary single (PI. 20. fig. 6). 



Arpacticus. Foot-jaws stout, terminated 

 by a claw ; ovary single. 



Alteutha. Foot-jaws small, simple ; body 

 flat ; a strong falciform appendage to 

 the fifth segment of the body on each 

 side (PI. 19. fig. 3). 



Tachidius, Dactylopus, Delavallia. 



Fam 2. DIAPTOMID^. Head consolidated 

 with the first joint of thorax ; foot-jaws 

 three pairs, well developed ; last pair 

 of legs differing in structure from the 

 others, and differing from each other in 

 the two sexes ; eye single, sometimes 

 pedunculated in the male ; right an- 

 tenna only with the swollen hinge- 

 joint in the male. 



Diaptomus. Cephalothorax and abdo- 

 men each of five segments fPl. 20. 

 fig. 38). 



Temora. Cephalothorax of five, abdo- 

 men of three segments. 



Anoinalocera. Cephalothorax of seven, 

 abdomen of four segments (PI. 19. 

 fig. 6). 



Dl08. 



Fam. 3. CETOCHILID^;. Head consolidated 

 with first joint of thorax; foot-jaws 

 three pairs, strongly developed ; eyes 

 two ; right antenna only with the 

 hinge-joint in the male. 



Cetochilus (PL 19. fig. 21). 



Notodelphys. Provisionally (PI. 19. fig. 



Legion 2. Branchiopoda. Branchiae at- 

 tached to the legs ; legs from four to sixty 

 pairs. 



Order 1. Phyllopoda. Legs from eleven to 

 sixty pairs in number, joints foliaceous 

 and branchiiform, chiefly adapted for re- 

 spiration and not motion ; eyes two or 

 three, sometimes pedunculated ; antennas 

 one or two pairs, neither adapted for 

 swimming. 



Fam. 1. BRANCHIPODIDA. Body not en- 

 closed in a carapace or shell ; antennae 

 two pairs, the inferior horn-like, and 

 with prehensile appendages in the 

 male ; legs eleven pairs. 



Artemia. Tail simply bilobed; no ap- 

 pendages at the base of the cephalic 

 horns. 



Branchipits. Tail formed of two plates, 

 cephalic horns with fan-shaped appen- 

 dages at the base (PI. 20. fig. 3). 



Fam. 2. ASPIDOPHORA. Body enclosed in 

 a shell; antennae one or two pairs; 

 legs more than eleven pairs. 



Apus. Shell flat, buckler-like ; antennae 

 one pair, small ; eyes sessile. 



Nebalia. Shell folded at the back ; an- 



