Occasional Papers of the Museum of Zoology 33 



One specimen from the savannah forests (H, III, b) has a 

 well-marked indentation on the basal lip of the aperture, and 

 many specimens show an indication of the same tendency. 

 These specimens quite closely resemble 0. fragilis (Morelet), 

 which Wagner (1907) places in his subgenus Leialcadia (or 

 Leicaladia?) of the genus Alcadia, 



Helicina {Tristramia) sephyrina Duclos (1833). — One hun- 

 dred one adults, mainly from leaves of trees and shrubs (up 

 to about 15 feet above ground) in the lowland jungle (H, I, 

 b) ; also found on shrubs, trees and elephant-ears in the par- 

 tially cleared region along Arroyo Hueyapam (H, II, a), and 

 on the leaves of shrubs and on cacti and yucca in the patches 

 of brush on the savannahs (H, III, b). Shells (mainly dead) 

 were also found on the ground (where they apparently aesti- 

 vate) in these places (H, I, a; H, III, a) and also in the bunit- 

 over region (H, II, b). 



This species aestivates with the operculum almost entirely 

 closed, but leaves a little crack between its lower edge and the 

 basal margin of the aperture (fig. i). Many specimens have 

 a slight depression on this portion of the aperture margin, with 

 an adjacent callus or tooth at the base of the columella. This 

 makes them look very much like the figures of //. deppeana 

 von Martens (1863). As this series of specimens also 

 approaches that species in sculpture (as figured), I am rather 

 inclined to believe that the latter is little more than a subspecies 

 of the present species. Apparently this condition of the aper- 

 ture is quite common throughout the family, although best 

 developed in Alcadia. The operculum of H. sephyrina has 

 the horny, inner layer well developed and almost scarlet in 

 color. The calcareous plate is very thin and is usually incom- 

 plete towards the parietal wall of the aperture, although the 

 columellar edge is thicker and better developed. 



