32 PROCEEDINGS OF THE NATIONAL MUSEUM vol.70 



keeled and the axial lines of the reticulum are prominent; the whole 

 is followed by two or more translucent whorls on which the keels 

 gradually disappear; suture distinct, not appressed; anal sulcus shal- 

 low, the fasciole indistinct; spiral sculpture of faint sparse spiral 

 striae only visible under magnification; axial sculpture practically 

 none; last whorl evenly rounded, with a long twisted, straight pillar, 

 with a minutely pervious axis; aperture narrow, outer lip thin 

 and sharp. Length, 4.6; diameter, 1.3 mm. U. S. Nat. Mus. Cat. 

 No. 107950. 



One specimen off Fernandina. 



PLEUROTOMELLA? VAGINATA, new species. 



Shell small, whitish, subtabulate, with a small brownish nucleus 

 of two whorls, the nepionic part of which is unicarinate and the axial 

 threads prominent, followed by four well rounded, strongly sculp- 

 tured whorls; suture distinct, constricted; anal sulcus deep but narrow, 

 the fasciole narrow and close to the suture, somewhat excavated 

 behind a prominent shoulder, giving a tabulate aspect to the whorls; 

 axial sculpture of (on the last whorl 11) rounded somewhat flexuous 

 ribs with much wider interspaces, the incremental lines obscure; spiral 

 sculpture of numerous equal fine threads, sometimes alternated in size 

 and sometimes not ; but in general covering more or less closely the 

 whole shell; aperture subovate, outer lip thin; pillar short, straight 

 with a previous axis. Length, 5.3; diameter, 2.3 mm. U. S. Nat. 

 Mus. Cat. No. 108305. 



Off Georgia, nine specimens. 



SPECIES WITH A SWIMMING LARVAL STAGE, THE NUCLEAR AXIALS OBSOLETE AND A CARINA EMPHASIZED 



MANGILIA ACROCARINATA, new species 



Shell small, acute, pale brown when fresh, with a short sharply 

 unicarinate nucleus of two, and six subsequent whorls; suture distinct, 

 appressed; anal sulcus shallow and rounded, the fasciole extending 

 between the suture and the shoulder of the whorl, flattish and smooth 

 except for incremental lines; axial sculpture of (on the last whorl 10) 

 extremely short ribs which appear chiefly as pointed nodules on a 

 peripheral minute keel and again as faint pustules on a thread near 

 the margin of the base; with wider interspaces; spiral sculpture of 

 the above mentioned thread and keel, and a few fine close threads 

 on the short canal; the general surface of the shell is polished with 

 a waxy luster; base flattish; aperture ovate, short; canal wide, pillar 

 attenuated in front, axis impervious. Length, 6.5; diameter, 2.7 mm. ' 

 U. S. Nat. Mus. Cat. No. 107944. 



Twenty specimens off Fernandina. 



