THE CYCLOPHO'RID LAND MOLLUS'KS OF AMERICA. 205 



Axial sculpture not strongly vermiculated. 

 Axial ribs of penultimate whorl straight. 



Sculpture rough and coarse ambiguum 



Sculpture not rough or coarse. 



Spiral bands present berendti 



Spiral bands absent sallei 



Axial ribs of penultimate whorl not straight. 



Base bicolor valerioi 



Base not bicolor. 



Axial sculpture of umbilical wall very coarse — nicaraguense 

 Axial sculpture of umbilical wall not coarse cookei 



APEROSTOMA (NEOCYCLOTUS) DYSONI DYERI, new subspecies 



Plate 28, Figures 31-33 



Shell gigantic for the species, helicoid, covered with an olivaceous- 

 buff periostracum. When denuded the early whorls are rose red, the 

 last soiled white; interior of aperture soiled white. The nucleus 

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

 turns are well rounded except near the summit, where they become 

 flattened, almost forming a groove, but immediately at the summit 

 they are again upturned and appressed to the preceding whorl. They 

 are rather coarsely sculptured by irregular, wavy, anastomosing, re- 

 tractively curved axial riblets. They are about as wide as the spaces 

 that separate them. Suture slightly impressed. Periphery well 

 rounded. Base narrowly, openly umbilicated, inflated, and marked by 

 the same type of sculpture as that which characterizes the upper sur- 

 face of the last whorl. This type of sculpture stops at the outer edge 

 of the umbilicus; the latter shows only coarse riblike incremental 

 lines. Aperture almost circular, drawn out into an obtuse angle at 

 the posterior angle of the aperture ; peristome simple, that of the outer 

 lip thin, while the columellar peristome is thickened and shows lines 

 of growth; the inner lip extends up over the parietal wall almost 

 undiminished, leaving a channel between the preceding turn and its 

 outer edge, which gives the last whorl a slightly solute aspect; how- 

 ever the whorl itself is not solute, for the apex of the projection at the 

 posterior angle is adnate to the preceding turn. The operculum is 

 typically neocyclotid. 



The type U.S.N.M. No. 215592, was collected by F. J. Dyer at La 

 Ceiba, Honduras. It has 4.7 whorls and measures : Height, 24.6 mm. ; 

 greater diameter, 33.3 mm.; lesser diameter, 23.3 mm. Height of 

 aperture, 15,4 mm. ; diameter, 16.8 mm. 



The following topotypes are also in the collection of the National 

 Museum : No. 322333, 3 specimens ; No. 424545, 10 specimens, and No. 

 404673, 2 specimens. 



The large size of this subspecies readily differentiates it from the 

 other subspecies of this group. 



428349—42 14 



