424 



of that species, presented to the Museum of Comparative 

 Zoology by Dr. Pilsbry, we find that in S. maya the riblets are 

 lower and more spaced, and that the several whorls are longer, 

 narrower, and more convex, making the spire more tapering. 

 In S. streheli the whorls are slightly shouldered below the suture 

 and the last whorl has approximately 45 riblets. To judge 

 from the figures, S. similaris (Strebel and Pfeffer) is also nearly 

 allied. 



Drymaeus shattucki, sp. no v. 



Description of shell. — Medium in size, long ovate-conic, perforate, moder- 

 ately solid. Color white or white with brownish spiral bands on the later 

 whorls, the tip of the apex pinkish brown. In the holotype the last whorl 

 has four bands, the lower two complete and rather broad, the upper two 

 narrow and almost obsolete, though with occasional darker blotches on the 

 uppermost band; on the penultimate whorl only the uppermost band is 

 visible and on the earlier whorls this band completely fades away. Whorls 

 63^ (in holotype), slightly convex, regularly increasing in size, the last slightly 

 more than half the total length of the shell. Spire lengthened and conic, apex 

 obtuse. Aperture nearly straight, ovate, relatively short (less than one-third 

 of the total length in holotype), showing the two lower bands inside. Peri- 

 stome simple, acute, unexpanded and somewhat thickened within. Columella 

 slightly oblique, triangularly reflexed over the umbilicus, impressed at its 

 insertion. Sutures moderately deep, not margined. Surface glassy, appearing 

 smooth, but showing fine, superficial, engraved, spiral lines under a strong 

 lens; embryonic whorls with typical Drymaeus grating of microscopic longi- 

 tudinal and spiral lirae. 



Length Width Length Ap. Width Ap. 



21.5 



10.0 



8.8 



5.5 mm. 



Holotype, adult 





23.5 



10.5 



9.5 



5.5 



Paratype, Tabi, adult 





17.5 



9.0 



8.0 



4.6 



Paratype, Tabi, immature 





17.0 



9.0 



8.0 



5.0 



Paratype, Chichen Itza, 

 mature 



im- 



15.5 



8.0 



7.0 



4.2 



Paratype, Chichen Itz^, 

 mature 



im- 



13.5 



7.5 



6.0 



4.0 



Paratype, Chichen Itzd,, 

 mature 



im- 



12.5 



7.0 



6.0 



4.0 



Paratype, Chichen Itza, 

 mature 



im- 



21.0 



10.0 



9.5 



5.5 



Paratype, Progreso, adult 





Holotype. — M. C. Z. no. 79396, from Chichen Itzd, Yucatan, collected by 

 J. Bequaert, June, 1929. 



Paratypes. — M. C. Z. no. 79409; data as above; Univ. of Michigan from 

 Chichen Itzd, collected by ¥. M. Gaige, January, 1930; A. N. S. Phila. no. 



