REPORT ON THE OSTRACODA. 45 



Bay, 15 to 20 fiithoms (Station 140); Balfour Bay, Kerguelen Island, 20 to 50 fathoms 

 (Station 149); Royal Sound, Kerguelen Island, 28 fathoms; off Prince Edward's Island, 

 50 to 150 fathoms; off East Moncoeur Island, Bass' Strait, 38 to 40 fathoms (Station 

 162) ; and off Amboyna, 15 to 20 fathoms. The type specimens were from "Australia, 

 the West Indies, and Turk's Island." 



[PI. I. fig. 2, a-d. a Carapace seen from left side, h from above, c from below, d from 

 front. Magnified 30 diameters.] 



Bythocypris, n. gen. 



Shell thin and fragile, smooth, reniform or subreniform ; left valve much larger than 

 the right, which it overlaps both on the dorsal and ventral margins. Antennae short and 

 stout; anterior pair (PI. V. fig. I, f) six-jointed, the first two joints very large, the 

 remainder small and bearing numerous long setae ; posterior pair (fig. 1, g) five-jointed, 

 having no "hyaline vesicle," the second and fifth joints about twice as long as the rest, 

 scarcely at aU tapered toward the apex, and terminating in about six stout curved setae, 

 one of which is much stouter than the others ; mandibles (fig. 1, h) armed with numerous 

 strong serrated apical teeth, and bearing a well-developed, four-jointed, and setiferous 

 palp, the first joint of which bears a rudimentary branchial appendage consisting of a 

 single stout seta. One pair of jaws only (?), consisting of four setiferous digits (fig. 1, i) 

 and a large branchial appendage, which is divided into two portions, the upper portion 

 ovate and bearing ten setae, the lower narrow, biarticulate, and provided with five slender 

 setae. Two pairs (?) of feet, the first (fig. l,j) bearing a single curved terminal claw and 

 about three short marginal setae, the second (fig. 1, h) rudimentary, consisting of a single 

 small joint with two stout setae. Post-abdominal rami (fig. \,l) of moderate size, curved, 

 and armed at the apex with one long and one short curved seta. 



Of this genus I have seen no perfect specimens, the description above given having 

 been di-awn up from the examination of a number of mutilated individuals. Most of the 

 dredged specimens consisted of single detached valves ; and the few which were perfect 

 so far as the shell is concerned contained in no case more than very imperfect remains of 

 the animal. Drawings of the various parts are given in Plate I., and from these it will 

 be seen that the species cannot be assigned to any hitherto described genus, those with 

 which it has most afiinity, however, being Cypris and Bairdia. From Cypris it is 

 distinctly separated by the unequal valves, the absence of a tuft of swimming setae on the 

 second pair of antennae, and by the quite rudimentary character of the branchial appen- 

 dage of the mandible-palp ; from Bairdia, to which, however, it approaches very closely, 

 by the rudimentary branchial appendage of the mandible (which in Bairdia (PI. I. fig. 2, 

 c) consists of a distinct trisetose joint); and by differences in the characters of the maxU- 

 laiy branchial apparatus and of the post-abdominal rami. From all other genera of 



