THE CY'OLOPHORID LAND MOLLUSKS OF AMEKHCIA 213 



No. 251716, seven specimens collected by Nelson and Goldman at 

 Campeche, Campeche, Mexico. 



The partially solute last turn, somewhat depressed spire, and spiral 

 lines will differentiate this from the other subspecies. 



APEROSTOMA (NEOCYCLOTUS) DYSONI SALLEI, new name 



Plvte 29, Figures 7-9 



1890. Cyclottis (Aperostoma) dysoni minor von Mabtens, Biologia Ontrali- 

 Americana, pi. 1, fig. 2 (not Cyolotus cormgatior minor Chitty, 1857). 



1923. Poteria (Neocyclotus) dysoni minor H. B. Baker, Occ. Pap. Mus. Zool. 

 Univ. Michigan, No. 137, p. 33. 



Shell very small, helicoid, the early whorls pale pinkish, the later 

 darker pink, and the last olive colored with axial darker streaks; 

 interior of the aperture bluish white. The nucleus consists of 2 

 small, well-rounded, smooth turns. The postnuclear whorls are some- 

 what inflated, strongly rounded ; the penultimate one marked by very 

 regular, retractively slanting axial riblets, which are as wide as the 

 spaces that separate them. On the last turn these riblets become 

 enfeebled and vermiculated and a little more distantly spaced. 

 Suture strongly impressed. Periphery well rounded. Base nar- 

 rowly openly umbilicated, inflated, well rounded, and marked on the 

 posterior half by the weak continuation of the sculpture character- 

 izing the upper surface of the last whorl. The umbilical wall shows 

 mere incremental lines. Aperture subcircular; peristome thin, the 

 outer effuse at the junction of the basal and outer lip; the inner 

 strongly curved and somewhat thickened. The parietal wall is cov- 

 ered by a moderately thick callus. There is an oval concave flexure 

 extending from the posterior angle to the columella. Operculum 

 typically neocyclotid. 



The specimen described and figured is one of two, U.S.N.M. No. 

 151376, collected by Salle in Yucatan. It has 4 whorls and measures : 

 Height, 11 mm.; greater diameter, 14.9 mm.; lesser diameter, 10.9 mm. 

 Height of aperture, 7 mm. ; diameter, 7.2 mm. 



U.S.N.M, No. 68008 contains another specimen without specific 

 locality. 



Its small size will readily differentiate this from all the other races. 



APEROSTOMA (NEOCYCLOTUS) DYSONI VALERIOI. new subspecies 



Plate 29, Figures 19-21 



Shell rather large, helicoid, all but the last whorl pale rose colored ; 

 the last whorl pale olive with the anterior half of the base lighter. 

 There are also axial streaks of dark olive. The nucleus consists 

 of 2 small, well-rounded, smooth turns. The postnuclear whorls 



