174 BULIiETICSr 181, UTSTITEiD SfTATEIS Ni^TTOOSHAiL IMUSETJM 



CYRTOTOMA GOLDMANI, new species 

 Plate 22, FiGtrRES 7-9 



Shell depressed-helicoid, covered with a straw-colored periostracum. 

 Nuclear whorls about 2, well rounded, forming a small elevated apex. 

 Postnuclear whorls well rounded and marked by coarse, somewhat 

 irregular, retractively slanting axial riblets, which vary in strength 

 and are slightly sinuous. Suture deeply impressed. Periphery well 

 rounded. Base openly umbilicated, well rounded, and marked by the 

 continuation of the ribs, which pass over the umbilical wall. Aper- 

 ture circular, slightly oblique. Peristome narrowly expanded, re- 

 flected, and marked with a very broad shallow U-shaped notch on 

 the parietal wall. The last whorl may be solute or adnate to the 

 preceding turn. 



The type, U.S.N.M. No. 523516, was collected by Maj. E. A. Goldman 

 at Mutaltoyuca, Puebla, Mexico. It has 6 whorls and measures: 

 Height, 13.9 mm. ; greater diameter, 20.9 mm. ; lesser diameter, 15.3 mm. 



U.S.N.M. No. 251719 contains 29 topotypes. Most of these are 

 smaller than the type. The smallest has 5.5 whorls and measures: 

 Height, 10.8 mm. ; gi-eater diameter, 16 mm. ; lesser diameter, 12.1 mm. 



This species is easily distinguished from G. mexicanum (Menke) 

 by its narrow peristome and very broad U-shaped sinus in the parietal 

 wall. 



CYRTOTOMA WALKERI (H. B. Baker) 



Plate: 22, Figures 10-12 



1928. Aperostoma walkeri H. B. Baker, Occ. Pap. Mus. Zool. Uuiv. Michigan, No. 

 193, p. 51, pi. 6, figs. 38-40. 



Shell small, depressed-helicoid, horn colored, with the early whorls 

 pinkish. The nucleus consists of about 2 small, well-rounded turns 

 forming a well-elevated apex. Postnuclear whorls strongly rounded. 

 The postnuclear whorls are somewhat inflated, strongly rounded, and 

 marked by very regular, retractively curved, rather strong axial rib- 

 lets, which are not as wide as the spaces that separate them. Suture 

 channeled. Periphery well rounded. Base broadly openly umbili- 

 cated, with the axial sculpture much reduced, almost absent on the 

 major portion of the base, but again strong on the umbilical wall, 

 where it about equals that on the spire. Aperture subcircular; per- 

 istome thickened and slightly reflected, almost with an indication of 

 a notch at the parietal wall. Operculum typically cyrtotomid. 



The specimen described and figured is one of two paratypes, 

 U.S.N.M. No. 515791, collected by H. B. Baker at Necaxa, Puebla, 

 Mexico. It has 4.5 whorls and measures: Height, 8 mm.; greater 



