EEPOKT ON THE OSTEACODA. 



105 



its range over the deep sea-bed, and like tliem also to be confined to great depths, the 

 shallowest reading in the foregoing list being 580 fathoms. 



[PL XVIII. fig. 5, a-e. a Shell seen from left side, h from above, c from below, d from 

 front. All magnified 50 diameters, e Right valve, magnified 40 diameters.] 



75. Cythere dasijdenna, n. sp. (PI. XVII. fig. 4, a-f, and PI. XVIII. fig. 4, a-f). 



Carapace tumid, ovate ; seen from the side, oblong, subovate or subquadrangular ; 

 greatest height situated near the front, and equal to about two-thirds of the length ; 

 anterior extremity boldly rounded, posterior narrower, rounded or subtruncate ; dorsal 

 margin sloping gently backwards from the front, which is elevated over the hinge-joint ; 

 ventral margin slightly convex ; the entire circumference broken into closely-set, but 

 short and blunt teeth ; seen from above, the outline is ovate, widest near the middle, 

 al)out twice as long as broad, lateral margins gently and evenly curved, extremities broad 

 and nearly equal, obtusely rounded or truncated ; end view broadly ovate, rounded ofi" 

 above, broad and centrally emarginate below. Shell-surface covered with closely-packed, 

 rather small, angular excavations, from the intervals between which arise numberless 

 (usually short and l^lunt) spines, the shell in every aspect presenting a rough appearance. 

 Length, l-40th to l-28th of an inch (-65 to "9 mm.). 



Like Cythere dictyon and Cythere acanthoderma, this species seems to occur in all 

 the deep places of the sea. The following list embraces all the dredgings in which I 

 liave noticed it : — 



Lat. 24° 20' jST., 



„ 38° 25' N., 



„ 28° 42' K, 



„ 9° 5' S., 



„ 46° 46' S., 



„ 34° 13' S., 



„ 39° 32' S., 



„ 11° 35' S., 



„ 5° 26' S., 



„ 2° 33' S., 



„ 36° 10' N., 



„ 38° 6' S., 



„ 33° 42' S., 



„ 42° 43' S., 



„ 52° 50' S., 



„ 48° 37' S., 



„ 37° 29' S., 



„ 32° 24' S., 



„ 2° 42' S., 



long. 24° 28' W., 



„ 35° 50' W., 



„ 18° 6' W., 



„ 34° 49' W., 



„ 45° 31' K, 



„ 151° 38' E., 



„ 171" 48' E., 



„ 144° 3' E., 



„ 133° 19' E., 



„ 144° 4'E., 



„ 178° 0' E., 



„ 88° 2' W., 



„ 78° 18' W., 



„ 82°11'W., 



„ 73° 53' W., 



„ 55° 17' ^\., 



„ 27° 31' W., 



„ 13° 5'W., 



„ 14° 41' W., 



[PL XVII. fig. 4, a-f. Figures a-d are drawn from a specimen from Station No. 317 



(ZOOL. CHALL. EXP. PART HI. 1880.) C 14 



