MUSEUM OF COMPARATIVE ZOOLOGY. 405 



Bymmctrical. A male intromittent orf^an is attached behind tlie base of the right 

 tentaclo, as in CucculinUke, AddiauniidcCj and Neritidce. It is .small, slender, 

 and subcylindiical. I have not seen the sol't parts of a female specimen. 



Cranopsis V erecta Dall. 



Shell strong, erect, with regularly ovate base, a smooth prominent nucleus, 

 and about one and a half cancellated whorls. Radiating sculpture of about 

 eighteen strong riblets, each pair enclosing another somewhat less strong, and 

 on each side of the latter a faint raised line, almost buried under the concen- 

 tric sculpture. The primary and secondary radii rise above the general level 

 of the concentric sculpture, the tertiary radii below it. The radii are strong 

 roundetl elevated threads. The concentric sculpture is of high close-set cord- 

 like ridges, which are closely applied to and pass over the radii, leaving relatively 

 deep pits in the space enclosed by the reticulations. The terminations of the 

 ribs ornament the outer margin of the base, which is radiately grooved for a 

 short distance under them. The interior is radiately striate with a tine groove, 

 extending from the front end of the fissure to the margin. Externally the 

 posterior slope starts from under a small beak, is straight and steep. From 

 the beak the dorsal outline is at first nearly horizontally forward, then, with a 

 bold round curve falls more steeply than the hinder slope. The fissure is 

 narrow, long, and sharp at both ends. A fasciole extends back from it toward 

 the beak, and a soldered fissure forward to the margin. Inside, the fissure is 

 surmounted by a short and flaring septum without buttresses, which extends 

 about one fourth the distance from the internal apex toward the front margin. 

 Externally the shell is grayish, and within subtranslucent white. Max. Ion. 

 of base, 10.0; max. lat. of base, 7.5; alt. of shell, 7.0 mm. 



Habitat. Off the coast of North Carolina, at Station 2601, in 107 fms., 

 gravel, bottom temperature 67°. 4 F. 



The fissure in this species is exactly intermediate between Cranopsis and 

 Puncturella proper, so far as position is concerned. It is a little farther for- 

 ward than in the typical Puncturella, and not quite as far as in Cranopsis. It 

 is manifestly most nearly related to the latter by the groove extending forward 

 from the fissure, and the sculpture is not unlike that of some specimens of 

 Cranopsis asturiana. From this it diff'ers by its profile, and the position and 

 form of the fissure and septum. The bluff" outline of the summit is far re- 

 moved from the conical form of P. noachina and from the low and graceful 

 arch of P. asturiana. 



Genus EMARGINULA Lamarck. 



Subgenus RIMULA Defrance. 



If the step from Cranopsis to Puncturella, or the reverse, is not very long, on 

 the other hand the distinction between Cranopsis and Rimula proper is not 



