1921] NATURAL SCIENCES OF PHILADELPHIA. 389 



tending to the axis on the last whorl. Aperture ver\^ shortly oval. 



Length 3.3, diam. 1.5 mm. 



Type and tAvo .young specimens No.4063 A.N.S.P.; with Scalar ia 

 77iinutissima Gabb and the preceding species. 



Aclis (Amblyspira) bartschiana Pils. and John.-. Plate XXXV, fig. 3. 



Proc. A. X. S. Phila., 1917, p. 174. 



Aclis (Hebetaclis) alta (Gabb) Plate XXVII, flg. 6. 



Attrictilina alia Gabb, Trans. Amer. Philos. Soc, XV, 187.3, p. 226. 



The surface of this shell is not plain, as stated by Gabb. It is 

 densely covered with slightly waved spiral striae, several of those 

 below the suture being larger. The apex is obtuse, the first whorl 

 being naticoid, glossy and smooth, with nearly level top and the tip 

 a little turned down; subsequent whorls are convex, separated by a 

 narrow, very deeply impressed suture. The thin concave columella 

 passes continuously into the parietal wall. 



Length 3.3, diam. 1.1 mm., 5| whorls. 



The type, no. 3170, is the largest of five specimens. 



The generic position of this graceful and delicate shell is not clear 

 to me, but it has some resemblance to Aclis. The obtuse summit 

 and the small number of relatively long whorls have caused its segre- 

 gation as the type of a new subgenus to be called Hebetaclis. The 

 aperture recalls that of Bcrthais Melvill, but the apical whorls differ. 



PYRAMIDELLIDAE. 



Doctor Bartsch's table of classification^^ has proved indispens- 

 ible in dealing with this group. L^nfortunateh' he has not yet 

 treated of the Antillean species. 



The Santo Domingan Turbonillas all conform pretty closely to 

 modern types, but part of the Odostomias do not fit readily into the 

 tables arranged for recent species. This may be due to our frag- 

 mentary knowledge of the recent Caribbean Odostomias. 



In addition to the species enumerated below, there are some 

 Turbonillas and Odostomias still to be worked out. 



Several species of TurboniUasinQl Odostomia have been described 

 by Miss Maury, Bull. Amer. Pal. V, pp. 147-151, but the figures 

 are so poor that no satisfactory comparisons with our species can 

 be made from them. 



3' A Monograph of West American Pyramidellidae, Bull. 68 U.S.N. Mus., 1909. 



