RECENT BRITISH OSTRACODA. 



463 



which is set with numerous long auditory cilia; last joint short, and bearing two setae, 

 which are much longer than the antenna itself. Lower antennse very robust, basal 

 portion large and thick, natatory branch very long, nine-jointed, the first three joints 

 elongated, the rest short, subequal, and set with long plumose cilia ; secondary branch 

 larger than usual, geniculated, three-jointed, last joint turned upwards. Basal portion 

 of the mandibular feet bearing at the apex a small tubercle, with two short hairs, 

 "forming a rudimentary incisive portion of the mandible ; penultimate joint shorter than 

 in Cypridina, the anterior marginal setse fewer and fasciculate. Pirst pair of jaws 

 slender, palp bearing simply a small trisetose lobe ; second pair of jaws having neither a 

 mandibuliform appendage nor clawed spines ; terminal lobes small, and bearing simple 

 hairs." Eyes large, subelliptical, far separated, and situated near the middle of the 

 shell. Animal swimming with long jerks. 



Philomedes inteuptjncta (Baird). (Plate XXXIII. figs. 10-13, and Plate XLI. fig. 3.) 



Cypridina interpuncta, Baird, Proc. Zool. Soc. Lond. part 18 (1850), p. 257, plate xvii. figs. 8-10 (An- 

 nulosa) . 



Philomedes longicornis, Lillj. De Crustaceis, p. 176, tab. xxvi. figs. 4-6, 14-16; Norman, Ann. & Mag. 

 Nat. Hist. vol. viii. p. 280, plate xiv. fig. 11 ; G. O. Sars, loc. cit. p. 107. 



Carapace, as seen from the side, oblong-oval, nearly twice as long as high ; dorsal 

 margin nearly straight, almost perpendicularly deflexed behind, gently curved down- 

 wards in front ; ventral margin gently convex. Anterior extremity obtusely pointed ; 

 oral notch situated below the middle, wide, its margins densely setose ; posterior ex- 

 tremity broad, obliquely truncate, bearing a short spine near its lower, and sometimes a 

 similar one near its upper termination. Outline, as seen from above, narrow ovate; 

 greatest width in front of the middle, equal to much less than half the length. End 

 view ovate, tumid, the notch showing as a diamond- shaped opening. The shell is 

 yellowish, horny, and translucent (except in old specimens), showing the animal clearly 

 through it ; surface marked with a fine reticulated pattern, similar to that of Candona 

 compressa (see Plate XXVI. fig. 26), but the meshes larger, often finely punctate. Second 

 joint of the upper antennae large, longer than the two following ; terminal setse longer 

 than the antenna itself. Natatory branch of the inferior antennae (exclusive of the setae) 

 about equal in length to the basal portion; first joint longer than the two following, 

 second about half the length of the third, which is nearly as long as the remaining six ; 

 first joint of the secondary branch short and stout ; second long, slender, slightly curved, 

 about equal in length to the first joint of the natatory branch, bearing three setce at the 

 middle of the external margin ; last joint shorter, very slender, and much curved, un- 

 guiculate, dilated at the base, apex obtuse. Third joint of the mandibular foot scarcely 

 half the length of the second, bearing a dense brush of plumose setae on the anterior 

 margin. Third pair of jaws terminating in a broadly triangular trifid lobe, densely clothed 

 with plumose setae. " Oviferous foot" terminated on one side by a rounded elevation, 

 on the other by a curved claw-like process ; setse very slender, minutely and symmetri- 

 cally spinous at the apices. Postabdominal laminae armed with about eleven curved 



