CYLICHNA. 295 



often eroded showing the inner porcellanous under the outer more 

 cretaceous layer, the extreme apex eroded in all the specimens ob- 

 tained ; aperture very wide in front, extremely narrow behind ; the 

 margin retreating from the columella to halfway between axis and 

 exterior, almost straight in front, then rising and continuing back- 

 ward nearly parallel to the axis, and falling away again obliquely 

 to the suture, forming an extremely narrow and deep notch ; body 

 with a thin deposit of white callus, columella hardly thickened, 

 spiral, passing without noticeable interruption into the anterior 

 margin ; outer lip sharp, thin. 



Lon. of shell 9'0 ; of aperture 7'5 ; max. lat. of shell 5"25 ; of 

 aperture 3'37 mm. 



Off Bequia, 1591 fms. ; off Guadelupe, 724 fras. 



Utricu/us (vortex var. f) domitus Dall, Blake Gastr., p. 47, pi. 

 17, f. 8. 



This shell has a distant resemblance to an Adaeon which it is 

 not, as is evident on inspection. It may prove a Cylichna when the 

 soft parts are known, reference until then being necessarily provis- 

 ional. It is peculiarly bevelled off behind and abrupt in front, 

 and is stouter than most shells of this group. It is possible that in 

 the young at some stage the nucleus may be entirely enrolled. It 

 quite distinct from anything recent or fossil which I find figured. 

 It is most nearly allied to U. f vortex Dall, which is a smaller, pro- 

 portionally more slender, cylindrical shell, with somewhat different 

 sculpture and a blunter spire. In the figure of U. f domitus the 

 wrinkles on the spire are not sufficiently emphasized as compared 

 with the lines of growth, nor is the difference in sculpture between 

 the body and the posterior aspect as sharply defined as it appears 

 under a good lens. This species differs from Utriculus spatlut Wat- 

 sou in form and in the absence of folds on the columella. It differs 

 from U. oUvlformis Watson in the proportion of the spire to the 

 whole length, in the unequal distribution and different character of 

 the sculpture. But I doubt if these species do not vary greatly, 

 and the discover}^ of intermediate links between them and U. vortex 

 Avould not surprise me in the least. {Dall). 



C. VORTEX Dall. PI. 21, fig. 7. 



Shell stout, rather solid, opaque white, short, the posterior fourth 

 bevelled off toward the bluntly rounded summit ; transverse sculpt- 

 ure consisting of occasional faint lines of growth, nowhere very 



