PROCEEDINGS OF THE NA TIONAL M USE UM. 1 5 



lii'iu; outer lip very fiexuons, witli a broad, ratber sljallow anal sulcus 

 behind, and arched forward in front of the peripheral rib; body wliite, 

 not callous; pillar thin, attenuated, and obli(iuely truncate in front, 

 concave, twisted, exhibiting- a pervious axis; canal shaHow, not prodnc- 

 ing a fasciole; operculum like that of MoJinia J'nclci. Height of sliell, 

 60; of last whorl, 48; of aperture, 38; maximum diameter, 2G mm, 



U. S. Fish Commission station 3415, in 1,879 fathoms, globigerina 

 ooze ; bottom temperature, 30° F. ; ott' Acaimlco, Mexico. 



2'y2)e.—:^o. 123099, U. S. N. M. 



The initiatory part of the operculum is spiral, as in jMohnia, thus 

 differing from the other deep-water l*leurotomi(be, wliich it in genera! 

 resembles. Tliey have tlie nucleus of the operculum apical and not 

 spiral. 



If it be thought necessary to use a sectional name for this species, it 

 might be called Steiraxis, differing from the other Pleurotomas as Molinia 

 differs from the species of Clirysodomus., 



PLEUROTOMELLA CASTANEA, new species. 



Shell polished, thin, resembling P. ciuffulata, Dall, of a chestnut- 

 brown color, fading to a paler pinkish-brown, with seven whorls, the 

 nucleus eroded, the early whorls with four or five flattened elevated 

 spirals with wider interspaces in front of a somewhat sloping anal 

 fasciole, more or less reticulated by narrow, slender, irregular, elevated 

 riblets in harmony with the lines of growth, and which form on the 

 fasciole delicate arches concave forward; the suture is ai)pressed; on 

 the body are about 20 spirals, stronger at the shoulder, smaller and 

 closer forward, the wide interspaces finely spirally striate, while the 

 most prominent spirals are undulate or obscurely nodulous; tlie trans- 

 verse sculpture is nearly obsolete and hardly to be distinguished from 

 the incremental lines; aperture elongate, oval ; outer lips thin, sharp, 

 crenulated by the sculpture, but not Urate; anal sulcus shallow, wide, 

 directly in front of the suture; body with a thin wash of callus; pillar 

 thin, gyrate, attenuated in front, forming a narrowly pervious axis, the 

 whole of a pinkish brown color; canal short, shallow, not recurved. 

 Height of shell, 53; of last whorl, 38; of aperture, 28; diameter, 23 mm. 



U. S. Fish Commission, station 3400, in 1,322 fathoms, ooze; temper- 

 ature, 36° F.; eastward from the Galapagos Islands. 



Type.— 1^0. 123134, U. S. N. M. 



This differs from P. cmgulata^ Dall, by its smaller size, more sloping 

 whorls, more delicate and reticulate sculpture, and by its pervious 

 axis. The animal is blind, and there is no operculum. 



NUCULA IPHIGENIA, new species. 



Shell large, solid, much like Iphigenia hrasiliana in outline, anterior 

 end pi'oduced, rounded, longer than the posterior; hinder end obliquely 

 truncate, attenuated ; beaks elevated, somewhat pointed, oi)isthogyrous ; 



