.~>X Yni.YAHIA. 



distinctly different shape ; but some of the younger specimens 

 of M. tteminnla, before they have put on the lip-callus audits 

 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, hns an evenly rounded outer lip and body- 

 whorl ; which recalls M.fusina. Its chief differences from M. 

 #<>minnla 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, 5'62 ; of last 

 whorl, 50; of aperture, 4'0. Lat. of shell, 3'0 ; of aperture, 

 1-37 mm. 



Yucatan Strait, 640 fms. 

 M. TORTICULA, Dall. 



Shell slender, shining, grayish waxen white, 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 very oblique folds, of 

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

 prominent ; outer lip simple, not reflected, slightly thickened, and 

 produced posteriorly, inwardly convex and externally concave 

 in correspondence with the bent axis ; aperture widest anteriorly, 

 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*75 ; of aperture, 8'0 ; Max. lat. of 

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



Station, 5, Lat. 241 5', Long. 764fl'.5, in 220 and 



152 fms., soft coral ooze, West Indies. 



The only shells normally arcuated in this manner which occur 

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

 very peculiar and highly characteristic appearance (Dall). 



