THE CYOLOPHORID LAND M0LLUSK9 OF AMERTCA 235 



on the last whorl, which gives the upper edge of this whorl a some- 

 what flattened aspect. The last whorl also is slightly decurrent near 

 the peristome. Suture strongly impressed. Periphery weakly angu- 

 lated. Base openly umbilicated, inflated, well rounded, and marked 

 by the continuation of the axial riblets, which fuse into heavier riblets 

 on the umbilical wall. Aperture subcircular, with a conspicuous 

 auricle at the posterior angle, which has a groove in its center ; peri- 

 stome simple ; outer lip thin ; the basal lip with 2 deep incisions, the 

 first of which marks the outer limit of the imibilicus, and the other is 

 about halfway between this and the periphery; the inner lip is mod- 

 erately thickened, while the parietal wall is covered by a moderately 

 strong callus, which renders the peritreme complete. 



The type, U.S.N.M. No. 190281, was collected by H. Pittier in the 

 Zhorquin Valley, Talamanca, Costa Rica. It has 4.5 whorls and 

 measures : Height, 15.4 mm. ; greater diameter, 23.7 mm. ; lesser diam- 

 eter, 16.4 mm. Height of aperture, 9.6 mm. ; diameter, 11.7 mm. 



This species can readily be distinguished from the other members 

 of the group having two notches on the basal area by its very much 

 smaller size. 



APEROSTOMA (APEROSTOMA) BISINUATUM (von Mortens) 



Plate 33, Figubes 5, 6 



1864. Cyclotus Usinuatus von Martens, Malak, Blatter, vol. 11, p. 113, pi. 3, 



figs. 1, 2. 

 1890. Cyclotus (Aperostomu) lisinuatus von Maktens, Biologia Centrali-Ameri- 



cana, p. 3. 

 1897. Neocpclotus {Neocylotus) Usinuatus Kobelt and Mollendokff, Nachrb. 



deutschen malak. Ges., vol. 29, p. 137. 



We have not seen this species and give a translation of von Martens' 

 description : 



Shell umbilicated, turbinate, solid, marked by closely spaced, un- 

 dulating, confluent riblets, yellowish brown unicolor. Spire conic, 

 somewhat acute. Wliorls 5, quite convex, the last one rounded, flat- 

 tened at the suture. Umbilicus quite narrow funnel-shaped, delimited 

 by an obsolete angle. Aperture diagonal, ovate, circular, angulated 

 above, bluish white within; peristome straight, obtuse, emarginate 

 above and below. Columellar margin arcuate; major diameter, 38.5 

 mm. ; lesser diameter, 29 mm. Height, 31 mm. Aperture, 20 mm. 



Discovered in a high plateau of Costa Rica by the late Hoffmann 

 who sent it to the Berlin Museum. 



This species is distinguished from the other members of the group 

 by the two notches, one at the outer limit of the umbilicus, and the 

 other diametrically across from it in the outer lip, a little posterior 

 to the middle. 



