678 DEEP WATER MOLLUSKS AND BEACRIOPODS—DALL. vol.xvil 



22; diameter of shell at posterior end of aperture, 8.5; length of aper- 

 ture, 9 mm. 



Station 3475, in 351 fathoms. No. 127122, U.S.N.M. 



This sjiecies has somewhat such a sculpture as the Autillean F.peri- 

 seelida, Dall, which is a much larger shell, and not a DriUia. The 

 most closely allied form I have seen is one dredged in 50 fathoms in 

 the harbor of Unalaska by the Albatross, but the latter is a shorter 

 and stouter and probably a smaller shell when adult. The specimens 

 of P. microscelida, though alive when collected, \^,ere much eroded, so 

 that the description has been made up from the patches of uninjured 

 suiface. By an accident to the jar the alcohol had evaporated, and 

 only the shell remained when received, so that nothing can be said as 

 to the soft parts. It is probable, however, that the species should be 

 referred to the genus Drillia. 



Genus MANGILIA. Risso. 



Subgenus PLEUitOTOMELLA, V e r r i 1 1. 



PLEUROTOMELLA GYPSINA, new species. 



Plate XXX, fig. 10. 



Shell small, subfusiform, moderately thick, white, covered with a 

 well-marked, unpolished brown epidermis; whorls six beside the 

 (decollate) nucleus, rapidly increasing; aperture slightly exceeding half 

 the total length; suture distinct, but not channeled or marked by any 

 elevated thread ; upper portion of the whorl, directly in front of the 

 suture, somewhat excavated, forming a wide anal fasciole; spiral 

 sculpture of, near the suture, fine, low, flattish, close-set threads, which, 

 beyond the fasciole, are gradually more and more distant until, near 

 the canal, the interspaces are thrice as wide as the threads; the sculp- 

 ture, as usual, is stronger on the upper whorls; transverse sculpture of 

 fine, even lines of growth, and (on the last whorl about 26) small, 

 distinct, even, very oblique ribs, with slightly wider interspaces, begin- 

 ning strong, but hardly nodular at the anterior edge of the fasciole, and 

 becoming obsolete on the base; on the upper whorls they reach the 

 suture; the last whorl is much the largest, the aperture and canal 

 rather wide, the anal notch arched and shallow, the outer lip project- 

 ing below it; pillar lip but slightly callous, interior of the aperture 

 smooth; pillar straight, attenuated in front, the canal obliquely cut off- 

 in front. Length of the shell, 23; width at the posterior angle of the 

 aperture, 8.5 mm. 



Station 3475, in 351 fathoms. No. 107015, U.S.N.M. 



The single specimen is a good deal eroded and has lost its nucleus. 

 The species is not unlike P. gypsata, Watson, from 700 fathoms near 

 New Zealand, but that species has only fifteen ribs, which do not reach 

 the suture on the earlier whorls. There are no remains of the soft 

 IDarts, but the shell looks like a small Pleurotomella. 



