58 VOLVAUIA. 



distinctly ditierent sliape ; but some of the younger specimens 

 oi 31. semiuula, before they have put on the lip-callus and its 

 angulation, appear much more similar, and suggest that the 

 range of variation may be wide enough to cover both. The 

 present form, with a proportionately shorter spire and longer 

 and wider aperture, h;is an evenly rounded outer lip and body- 

 whorl ; which recalls M. fasina. Its chief ditterences from 31. 

 seminala consist in those features which accompany the should- 

 ering of the whorls and the thickening of the outer lip, which in 

 this form seems to be always evenly rounded, arched forward, 

 and hardly thickened ; it is slightly but distinctly reflected, and 

 the canal is slightly recurved. Long, of shell, ii"62 ; of last 

 whorl, 5 0; of aperture, 4'0. Lat. of shell, 3"0 ; of aperture, 



1"37 mm. 



Yucatan Strait, 040 fms. 

 M. TORTICULA, Dall. 



Shell slender, shining, grayish waxen Avhite, of about five 

 whorls ; spire roundly pointed, slender, covered in the adult with 

 a complete coat of translucent glaze almost obscuring the sutures ; 

 last whorl somewhat appressed between the junction of the outer 

 lip and the suture ; turns somewhat laxly coiled ; surface per- 

 fectly smooth; axis laterally curved, with the convexity' to the 

 left, so that the spire and the canal both point to right of a 

 straight line when the shell is in its natural position ; aperture 

 long and narrow ; columella with four ver^- oblique folds, of 

 which the one behind the anterior fold is a little the most 

 prominent ; outer lip simple, not reflected, slightl}- thickened, and 

 produced posteriorly, inwardlj^ convex and externally' concave 

 in correspondence with the bent axis ; aperture Avidest anteriorl}^, 

 making the canal very open ; no callus on the body-whorl, which 

 is joined by the outer lip at an exceedingly acute angle. Long, 

 of shell, 11-5; of last whorl, 9'15 ; of aperture, 8-0 ; Max. lat. of 

 shell, 3"75 ; medium lat. of aperture, 1"0 mm. 



Station 5, Lat. 24°! 5', Long 7()C4fl',r), in 320 and 



152 fms., soft coral ooze, West Lnd/'es. 



The only shells normally arcuated in this manner which occur 

 to me are some species of Eulima. The twist gives the shell a 

 very peculiar and highl}- characteristic appearance (Dall). 



