NO. 1483. 



UROCOPTID MOLLUSKS—BARTSCH. 



145 



Cienaga Grande, Coahuila, Mexico. The perfect specimen has 12 

 whorls and measures: Length, 23 mm.; diameter of eighth whorl, 

 6.5 mm.; diameter of penultimate whorl, 5.6 mm. 



HOLOSPIRA (HAPLOCION) MINIMA von Martens. 



There are two lots of this species in the collection of the U. S. 

 National Museum. One, Cat. No. 126124, U.S.N.M., collected by G. 

 Eisen, in Sonora, Mexico, contains 5 specimens. The other. Cat. No. 

 56960, U.S.N.M., 6 specimens, donated by W. M. Gabb, comes from 

 Hermosillo, Sonora, Mexico. These specimens giv^e the following 

 measurements: 



Measiirements of Holospira { Haploclon) minima. 



HOLOSPIRA (HAPLOCION) TOWNSENDI, new species. 

 Plate IV, lig. 13. 



Shell white, cylindric-conic. Nuclear whorls two, veiy large, pro- 

 jecting decidedly beyond the outline of the spire. The tirst of these 

 is large, inflated, and well rounded. The second is a little more 

 depressed and decidedly keeled in the middle. Terminal cone long 

 and gentl}" tapering, composed of the seven whorls succeeding the 

 nucleus. These whorls are somewhat overhanging, well rounded and 

 ornamented by man}^ equal and equally spaced obliquely backward 

 curved ribs. Whorls of the cylindrical portion well rounded, having 

 the ribs a little more distantly spaced on the anterior than the pos- 

 terior volution. There appear to be about 38 ribs upon the third 

 whorl (i. e., the first postnuclear whorl), 60 upon the tenth and 38 

 upon the penultimate volution. Sutures well impressed. Periphery 

 of the last turn angulated, having the ribs somewhat strengthened 

 at this place. Base quite short, rounded, marked by the continuation 

 of the ribs, which taper gradually as they pass into the rather deep 

 umbilical rimation. Last portion of last whorl very shortly free, the 

 expanded portion of the peristome almost touching the outer wall of 

 the preceding turn. Aperture almost circular, with a broadly ex- 



