612 proceedings of the academy of [nov.^ 



Descriptions of New Species. 



Helicina crosbyi n. sp. Plate XIX, figs. 1, 3, 8. 



Helicina crosbyi Purves, Bull. Mus. Roy. Hist. Nat. Belg., Vol. Ill, 1884, 

 p. 310. Name only. No description or figure. 



Shell depressed, conic, of about four and one-half whorls, marked 

 by growth-lines, periphery somewhat keeled up to the last whorl, 

 where it becomes rounded. Outer lip much thickened and heavy, 

 the inner lip expanding and covering the umbilicus with a heavy 

 callus. The thickened outer lip rises abruptly from the last whorl 

 in a ridge, which continues to beyond the columella and forms the 

 border of the heavy callus of the inner Yvp, but this elevation of the 

 lip dies away and the callus of the inner lip thins down until it reaches 

 the level of the base of the last whorl. Slope of the spire even, the 

 sutures not depressed, spire somewhat convex. Operculum unknown. 



Alt. 7.7 mm., cham. 11 mm. Types A. N. S. P. Collection No. 

 109,109. 



This species was named by Purves H. crosbyi, but apparently 

 never described nor figured. It is easily identified a's the species 

 referred to by M. Purves, as it occurs fossil in the "horizontal marls'* 

 at several points noted by him, but is unknown in the living state 

 and appears to be extinct. The "semi-fossil" shells are entirely 

 without pigment, so that what colors the original shell possessed must 

 remain unknown. The form of the heavy callus and the great 

 thickening of the outer lip which characterize this species recall the 

 lip and callus of the Jamaican Helicina neritella angulata C. B. Ad., 

 which, however, differs from this species in having the angulation 

 of the periphery continued on the last whorl out to the lip. 



The specimens were collected at St. George's Church and at Hodge's 

 Bay, Antigua. Pleistocene. 

 Scala (Sthenorhytis) antiguensis n. sp. Plate XX, fig. 9. 



Shell turbinate, of about five whorls, rapidly enlarging; the suture 

 impressed, whorls rounded, crossed by about sixteen varices which 

 are acute edged and rise abruptly from the whorl. The intervarical 

 spaces are crossed by five raised revolving cords with a secondary 

 sculpture of fine, somewhat irregularly spaced revolving lines and 

 crossed by radial lines parallel to the varices. This secondary 

 sculpture which covers the varices also, is best observed with a lens. 

 From the excavated form of the base of the shell, it is probable that 

 the mouth was circular, but this portion of the shell is imperfect. 

 Alt. 30 mm., diam. 19 mm. From the Hodge's Hill limestone 

 (Antigua formation), Hodge's Bay, Antigua. Oligocene. 



Type A. N. S. P. Collection, invertebrate fossils. No. 1,645. 



