MUSEUM OF COMPARATIVE ZOOLOGY. 267 



416 fms., near Grenada, bottom temp. 42°.5 F. ; and many stations of the 

 U. S. Fish Commission off the coast of New England. 



The specimens are smaller, on the whole, and somewhat less rude, but other- 

 wise do not differ from those from more northern stations. 



Genus CRYPTODON Torton. 



Cryptodon orbiculatus SEonENZA. 



Verticordia orbiculata Seguenza, Men. Vert., p. 9, 1876. 

 Axinus orbiculatus Jeffreys, P. Z. S., 1881, p. 703, pi. Ixi. fig. 5. 



A shell (one valve) which seems to agree with Seguenza's description was 

 dredged at Station 220, in 116 fms., near Santa Lucia, but I cannot make out 

 such a sculpture as is figured by Jeffreys on the plate referred to. There are 

 extremely fine radiating rows of dots, and a powdery surface over them, but I 

 cannot make out riblets and pores such as are figured. 



Cryptodon flexuosus Moxtagu. 

 One valve occurred at Station 262, in 92 fms., near Grenada. 



Cryptodon pyriformis, n. s. 

 Cryptodon ? obesus Verrill, Dall, Bull. M. C. Z., IX. p. 136, 1881. 



Shell thin, white or flesh-color, subtranslucent, not very convex, when 

 fresh with an appearance as of white dust on the exterior surface, beaks high, 

 narrow, rather pointed, more or less recurved, with a depressed lanceolate 

 lunule in front of them; anterior dorsal slope concave, steep, terminating 

 about half-way between the umbo and the base in a rounded angle; posterior 

 slope shorter, slightly convex, then inflexed to meet the posterior rib which 

 has its steepest side posterior and anteriorly passes into a wider flexure of the 

 surface which lies between the rib and the middle part of the shell; the base 

 is rounded and produced in the middle line, the curve extending from the rib 

 to the anterior angle; the outer surface is marked by faint lines of growth 

 and obscure malleations; the interior is smooth, exhibiting the flexuosities; 

 the hinge-line is narrow and flattened under the beaks, perfectly edentulous; 

 the muscular impression faint and elongated. Lon. 11.2, alt. 14.0, diam. 

 6.5 mm. A larger but imperfect specimen must have been 17.0 mm. high. 



Habitat. Yucatan Strait, 640 fms. (broken valves) ; also at the Fish Com- 

 mission Stations 2646 and 2678, off the Florida and Carolina coasts, in 85 and 

 731 fms. 



This fine species was doubtfully referred to C. obesus in my preliminary 

 report. Since then I have had the opportunity of examining an unparal- 

 leled series of this genus comprised in the Jeffreys collection, besides a good 



