88 BULLETIN 181, UNITED STATES NlATIONlAiL MUSflEUM 



specimen that I have seen. It has 4.2 whorls and measures: Height, 

 7.9 mm. ; greater diameter, 12.7 mm. ; lesser diameter, 9.0 mm. 



PTYCHOCOCHLIS WELCHI, new species 



Plate 13, Figxjbes 28-30 



Shell small, depressed-helicoid, the early whorls red, the rest oliva- 

 ceous with a chestnut-brown tinge; interior of the aperture bluish 

 white. The nucleus consists of 1.2 well-rounded, smooth turns. The 

 first postnuclear turn is well rounded and marked by poorly devel- 

 oped, somewhat irregularly distributed, feeble axial riblets. On the 

 remaining turns these riblets become more and more irregular owing 

 to the rugate ridges marking the surface. Beginning with the sec- 

 ond postnuclear whorl, these ridges gradually develop; they extend 

 from almost at the summit to the periphery and have a decidedly 

 protracted slant. They are not quite as wide as the low spaces that 

 separate them, and are crossed by the slender riblets. Suture strongly 

 constricted. Periphery well rounded. Base openly umbilicated with 

 a moderately strong keel marking its outer limit. The base is marked 

 by weak, retractively curved ridges, which are best developed on the 

 early part of the last turn and become obsolete on the later portion. 

 They are strongest near the periphery. The umbilical wall is marked 

 by strong, fairly coarse riblets. Aperture circular, protracted into 

 a decided angle at the posterior angle. Peristome thin. Operculum 

 typically ptychocochlid. 



The type, U.S.N.M. No. 535966, was collected by d'Alte A. Welch 

 at his station A7, at Hardware Gap, St. Andrew Parish, Jamaica. 

 It has 4.2 whorls and measures : Height, 10.6 mm. ; greater diameter, 

 15.0 mm. ; lesser diameter, 11 mm. 



Nine topotypes are in Dr. Welch's collection. This species suggests 

 P. manchesterensis, from which its coarser sculpture on the upper sur- 

 face, more pronounced umbilical keel, and feebler sculpture of the base 

 will readily distinguish it. 



PTYCHOCOCHLIS MANCHESTERENSIS, new species 



Plate 13, Figubes 19-21 



Shell of medium size, lielicoid, pale chestnut-brown. Nuclear 

 whorls 1.2, well rounded, smooth. The first postnuclear whorl is 

 strongly rounded and marked by slender, slightly retractively curved, 

 rather closely spaced axial riblets. These axial riblets become 

 stronger and less regular on the succeeding postnuclear turn. On 

 the last whorl they are decidedly sinuous. Beginning with the sec- 

 ond postnuclear turn in addition to the axial riblets, the whorls are 

 marked on the anterior two-thirds by decidedly obliquely slanting. 



