502 PROCEEDINGS OF THE ACADEMY OF [Aug.^ 



short-oval, the. outer lip thin, short, the body erased white, the 

 pillar gyrate and minutely pervious; canal very short, wide, and 

 slightly recurved; operculum with a small subspiral nucleus. Length 

 of shell 31; of last whorl 20 ; maximum diameter 14 mm. 

 Bering Sea, off the Pribiloff Islands in 1,771 fathoms. 



Mohnia vernalis "■ sp. 



Shell small, thin, white under a light green periostracum, of about 

 seven whorls; the apex apparently blunt, but always more or less 

 eroded; the nepionic whorls with a few spiral grooves, the following 

 whorl or two with about 16 rather prominent short ribs, most promi- 

 nent at the periphery, with narrower interspaces crossed by fine 

 spiral striae with wider interspaces; the ribs rapidly become obsolete 

 and on the last three whorls are absent, the surface being then only 

 marked by very arcuate incremental lines, the striae becoming obso- 

 lete, except on the base near the canal where there are a few coarse 

 spirals; aperture short-ovate, the outer lip thin, sharp, the body 

 erased, the canal short, wide, slightly recurved, the pillar gyrate, 

 minutely pervious; the operculum with a subspiral nucleus. Length 

 of five whorls (the apex being eroded) 21 ; of last whorl 14; maximum 

 diameter 10 mm. 



Off Tillamook Bay, Oregon, in 786 fathoms. 



Mohnia siphonoides n.'sp. 



Shell solid, rotund, white, with an olivaceous polished periostracum, 

 and with about six whorls; apex eroded, apparently blunt; sculpture 

 of faint incremental lines and sparse zigzag oljsolete ridges recalling 

 those of Tritonofusus hypolispus Dall, but less distinct; whorls 

 rather flattish, aperture ovate; outer lip slightly reflected, body with 

 a thin layer of callus, pillar gyrate, not pervious, canal short, recurved. 

 Operculum with a small subspiral nucleus. Length (eroded) 34; 

 length of last whorl 26; maximum diameter 15 mm. 



Bering Sea, off Pribiloff Islands, in 987 fathoms. 



If it were not for the operculum, this shell would certainly be 

 referred to Tritonofusus. 



Mohnia exquisita n. sp. 



Shell delicate, white under a greenish periostracum, with about 

 seven whorls; suture not appressed; axial sculpture of incremental 

 lines which cut the spiral keels and minutely serrate their edges 

 occasionally; spiral sculpture, fundamentally of two prominently 

 elevated keels; one at the shoulder recurved, the other vertical to 

 its base; with ten or twelve not prominent spiral cords on the base. 



