OSTRACODA. 391 



Sub-order 2. PODOCOPA.* 



The shell is not notched in front, and, in accordance with the 

 creeping habit, is flattened along the ventral border. The 

 second antenna articulates with a prominence at the side of 

 the upper lip. The endopodite forms the strong leg-like ter- 

 mination of this appendage, while the exopodite is short, and 

 generally much reduced. The mandible has a short palp 

 which may be biramous (Fig. 253). 



Fam. 4. Cypridae. Shell generally not sculptured. The endopodite 

 of the second antenna is strongly flexed on the basal joint and terminates 

 in strong claw-like setae ; the exopodite is reduced to a small scale. The 

 fovirth pair of appendages (1st maxillae) is jaw-like, having masticatory 

 processes from the basal joint, a short palp and a large respiratory fan 

 (epipodite). The next pair has a masticatory process and a respiratory 

 fan on the basal joint, a short exopodite directed forwards and a longer 

 claw -like endopodite directed backwards. The latter is modified as a 

 prehensile organ in the male. The sixth pair is long and pediform : the 

 seventh, is also pediform but slender and directed dorsally. The halves 

 of the caudal fork slender and rod-like, bearing setae at their ends, or 

 reduced. There is no heart. The testes and ovaries are partly contained 

 between the lamellae of the shells. In the males a peculiar ejaculatory 

 apparatus formerly known as the " mucous gland," invests the vas 

 deferens near its termination. The greater number of species live in fresh 

 water. Notodromas Lilljeb., with the three parts of the median eye 

 widely separated, Cypris Mull., Stenocypris Sars (Fig. 253), Pontocypris 

 Sars, Pontocypria Miill., Ilyodromus Sars, Argilloecia Sars, Paracypris Sars, 

 Candona Baird, Macrocypris Brady, Aglaia Brady, Goniocypris Brady, 

 Metacypris Brady, Nesidea Costa. 



Fam. 5. Bairdiidae. A small group of marine Podocopa with char- 

 acters intermediate between those of the Cypridae and Cytheridae. The 

 shell is frequently much arched dorsally and the two halves are unsym- 

 metrical. The crop forms a well-developed masticatory mill. Bairdia 

 McCoy, Bythocypris Brady, Anchistrocheles Brady and Norman. 



Fam. 6. Cytheridae. Shell strongly calcined. Second antenna like 

 that of the Cypridae, but the exopodite is an elongated and slender organ, 

 bent at the tip, and perforated by the duct of the large unicellular 

 " spinning-gland," the secretion of which is, according to Muller, spread 

 as a web of fibres over surrounding objects. The fourth pair of appendages 

 (mx. 1) has a masticatory function, but the three following are exclusively 

 locomotory. Divisions of the caudal fork small and weak. There is no 

 heart and neither the testes nor ovaries extend between the lamellae of 

 the shell. All the species are marine. Cythere O. F. Miill., Eucythere 

 Brady, Cythereis Sars, Cytherideis Jones, Cytheretta G. W. Miill., Micro- 

 cytherura G. W. Miill., Cyprideis Jones, Krithe Brady, Crosskey and 

 Robertson, Cytheropteron Sars, Loxoconcha Sars, Pseudoloxoconcha G. W. 

 Miill., Cytheroma G. W. Miill., Xestoleberis Sars, Microxestoleberis G. W. 

 Miill., Paracytheridea G. W. Miill., Polycheles Brady, Cytherura Sars, 



* See footnote on p. 389. 



