425 



61514, from Tabi, Yucatan, collected by Heilprin, Baker, Stone and Ives, 

 February-March 1890; and M. C. Z. no. 47197, from Progreso, Yucatan, 

 collected by J. L. Cole, 1904. 



Remarks. — This species belongs to the group of D. multi- 

 lineatus (Say) and is most closely allied to D. tropicalis (Morelet). 

 D. shattucki is dextral, while D. tropicalis is sinistral; but a 

 comparison of the two species, which we have been able to 

 make through the kindness of Dr. Pilsbry, fails to disclose any 

 other differences. Possibly we have here a case where a species 

 exists in a dextral and a sinistral race, a supposition which could 

 only be proved by experiment. Meanwhile it seems safer to 

 regard D. shattucki as specifically distinct, since sinistrality is 

 very exceptional in the genus Drymaeus. There is also a remote 

 possibility that D. shattucki might not be separable from D. 

 hondurasanus (PfeifTer), which is not known to us. 



The specimens from Tabi were sent to us by Dr. Pilsbry who 

 at one time listed them as Bulimulus dysoni (Pfeiffer); but he 

 later recognized that they belonged to a different genus. The 

 grated sculpture of the embryonic whorls at once removes D. 

 shattucki from Bulimulus. 



The snails recorded by E. von Martens (1893, Biol. Centr.- 

 Amer., Moll., p. 227) from Yucatan as Otostomus moricandi var. 

 hyalino-alhidus (Fischer and Crosse), may possibly have been D. 

 shattucki. 



Choanopoma gaigei, sp. no v. 



Description of shell. — Medium in size, acuminate, elongate-conic, narrowly 

 umbilicate. Color pale brown, with spiral bands of mahogany red, the bands 

 usually irregularly broken, more strongly developed on the last two whorls. 

 Whorls 6, convex, regularly increasing in size, and often all preserved in adult 

 specimens; sometimes only the embryonic whorls lost. Spire acute, but the 

 apex truncate, the first whorl being depressed. Aperture entire and nearly 

 circular. Peristome duplex: inner rim sharp and circular; outer rim reflected, 

 somewhat wavy, and forming a slight rounded expansion near the parietal 

 angle. Sutures deep, not channeled, strongly but finely and regularly beaded. 

 Sculpture of both axial and spiral threads. Embryonic whorls smooth; third 

 and fourth whorls with strong, axial riblets, regularly spaced. On the re- 

 maining whorls the spiral sculpture gradually approaches and eventually 

 equals the axial riblets, which on the last whorl are more crowded. Under 

 the lens the last whorl is finely reticulate. The fine sutural beading is caused 

 by the insertion and slight thickening of the axial riblets. Operculum calci- 

 fied, paucispiral, circular, composed of three whorls; occasionally the edge 



