88 BULLETIN OF THE 



young specimens) a still smaller rather rounded thread, which forms the pe- 

 riphery of the base, and which a slight expansion of the last half-whorl in the 

 adult covers up, so that there are only three spirals visible on this last small 

 portion ; base nearly flat, with one rather marked spiral within the periphery, 

 defined by a groove on either side, and between this and the canal numerous 

 fine submicroscopic spiral striae ; in the earlier whorls the spirals are waved 

 or even tuberculated by the transverse undulations, the large spiral most so 

 and the anterior one least so, varying in amount in different specimens ; in a 

 strongly sculptured specimen which was selected for description as living and 

 perfect, the transverse sculpture (of about twenty faint undulations) is stronger 

 than the spirals during the three or four apical whorls, gradually becoming 

 fainter until on the eighteenth and succeeding whorls it is only visible be- 

 tween the spirals under a strong magnification ; for the greater part of the 

 shell the spirals are not tubercled, but waved or slightly swollen at the inter- 

 section of the transversals, which last become fainter and more numerous from 

 whorl to whorl, and on the base are not indicated, or only by moderately dis- 

 tinct lines of growth. On another larger specimen the tuberculations or un- 

 dulations are perceptible only on the earlier third of the shell, and on the 

 remainder are represented only by the lines of growth ; in this specimen the 

 spirals also are lese distinctly marked in the latter part of the shell, the two 

 intermediate ones suffering most diminution ; on the surface spiral stria? exist, 

 which are hardly to be detected on the first-mentioned strongly sculptured 

 specimen ; the base is about the same in both. The sharp outer lip does not 

 appear to be ever thickened, but at certain periods it is slightly reflected and 

 this excessively thin edge is visible like a varix here and there on the whorls, 

 although it hardly rises above their surface ; the aperture is squarish, short, 

 and wide ; the inner lip glazed, but not thickened ; the outer lip concavely 

 waved laterally and with the basal edge slightly produced ; the pillar solid, 

 very short, strongly spirally twisted and forming a short but very distinct 

 canal abruptly bent to the left ; operculum so far retracted as to be inac- 

 cessible ; soft parts indicated by a blackish tinge perceptible through the 

 shell. Lon. of shell, 10.5 ; of last whorl, 2.0 ; of aperture and canal, 1.5. Lat. 

 of shell, 1.75 ; of aperture, 0.9. Lon. of longest specimen when perfect, 

 13.25 mm. 



Station 5, 229 fms. Station 20, 220 fms. 



The genus Cerithiopsis appears to be at present ill defined, the character of 

 the operculum used by Forbes being illusory, if Sars's figure is correct ; the dif- 

 ferences of dentition between this form and Bittium appear quite sufficient to 

 distinguish it, however, if other species agree. Nevertheless, it seems at pres- 

 ent impossible to fully define either genus or to distinguish by the shell (ex- 

 cept approximately) between species of Bittium and Cerithiopsis as these names 

 have heretofore been applied. The differences in the soft parts which have 

 been mentioned may exist, but like the asserted differences in the opercula 

 prove on more thorough inspection to be partly transitional or specific charac- 

 ters. It will be understood, therefore, that the above and succeeding species 



