NO.H39. DEEP-WATER MOLLUSCA VF.VUI1.L AXD KUSH. 801 





which are most distinct OH the rostrum. The hinge-margin is thin. 

 The right valve has a thin, low, much elongated posterior lateral tooth 

 which runs nearly parallel with the dorsal margin, above which it pro- 

 jects in a broad curve; the cartilage-plate is small, very oblique, and 

 closely united with the tooth from which it is separated by a faint, curved 

 notch; no buttress. In the left valve there is no lateral tooth, and the 

 cartilage-plate is very small, slightly prominent, with a curved inner 

 edge. The inner surface of the shell is smooth and the muscular scars 

 are faint. 



Length of an average specimen, 13 mm.; height, 8 mm.; breadth, 6.5 

 mm.; beak to end of rostrum, 8.-") mm.; beak to anterior end, 6 mm. 



This species is allied to C. glacialls, from which it differs in its more 

 swollen form, more oblique anterior end, more prominent ventral mar- 

 gin, more clearly denned rostrum, and straighter postero-dorsal margin. 

 The hinge shows still more decided differences; the lateral tooth of the 

 latter is stouter, more prominent, and less prolonged; the cartilage- 

 plate is smaller and less distinctly defined. From C.fraterna it differs 

 in being less produced ventrally and in having a longer rostrum with 

 much straighter dorsal margin and a much longer lateral tooth. 



This is a common species off Marthas Vineyard and has been taken 

 at about fifteen stations between N. lat. 40 10' 15", W. long. 70 26', 

 andN. lat. 39 50', W. long. 70 5-1' IS", in 63 to 155 fathoms, 1880-1884. 

 A broken valve, station 362, N. lat. 42 1', W. long. 69 34', in 106 

 fathoms, 1879, is also referred to this species. 



CUSPIDARIA PARVA, new species. 

 (Plates LXXIY, tig. 9; LXXVII, tig. 7.) 



Shell small, delicate, elongated, inequivalved, having a general resem- 

 blance in form to the very young of C. obesn and C. fraterna. Umbos 

 small, rather prominent; beaks small and incurved. The autero-dorsal 

 margin is moderately convex and slopes regularly to the evenly rounded 

 anterior end; ventral margin very broadly rounded, with a decided 

 incurvature at the base of the rostrum, corresponding to the marked 

 depression of the surface; postero-dorsal margin slopes rapidly at 

 first and is usually concave along the rostrum, which is moderately 

 long (the length varies in different specimens), narrow, with an obtusely 

 rounded or subtruncated end. It is crossed by a distinct diagonal 

 ridge, above which there are several small, raised, radial lines; the 

 surface is elsewhere nearly smooth or presents a microscopic, faintly 

 granulose appearance. The left valve is the larger and considerably 

 overlaps the right along the ventral margin and siphonal region; the 

 right overlaps the left along the postero-dorsal margin; the rostrum 

 is a little bent toward the left in some specimens. The hinge-margin is 

 delicate, with the anterior margin a little everted; cartilage-plate 

 minute, sunken, in the right valve well separated from the prominent, 



Proc. N. M. vol. 



