Occasional Papers of the Museum of Zoology 45 



not adnate to the body whorl. If this process should be con- 

 tinued long enough, I have no doubt it would result in the 

 complete freedom of the peristomal margin. 



The shells of the form mexicamwi are more variable in 

 appearance than are those of sallcanum. The growth-wrinkles 

 of the former are quite irregular, and the epidermis is usually- 

 eroded toward the tip, which may be somewhat chalky in 

 appearance. Specimens measure: 



Altitude Greatest diameter Height aperture Diameter aperture 



ZONITIDAE 



Guppya gimdlachi (Pfeiffer) (1840). — One hundred three 

 specimens ; on ground among humus and decaying leaves in 

 the lowland forests (H, I, a) ; and a few feet above ground, 

 on young palms in the lowland forests (H, I, b) ; on elephant- 

 ears along Arroyo Hueyapam (H, II, a), and on cacti in the 

 savannah brush (H, III, b). Apparently, it is a ground spe- 

 cies, which moves up into the lower vegetation in the wet 

 season. 



As the dried animals were still in some of the shells, two 

 preparations of the jaw and radula were made and examined. 

 The jaw (fig. 3) is quite similar in structure to that of Euconu- 

 lus, but has a more nearly semicircular outline. The formula 

 of the radula (fig. i) may be expressed: 



I 5 24 2 I 



C — ; L — ; M — H h — ; or 27-5-1-5-27. 



33341 

 The central has broader and shorter cusps than Euconulus. 

 The first four laterals are practically the same shape as the 

 central; in fact, I could not determine which was the central 



