Vll CO PTID MOLL USKS—BA It TSCIL 



143 



There are two specimens of this species in the collection of the 

 U. S. National Museum, Cat. No. 1S79S1, which were received from 

 Prof. A. L. Hcrrera. They were collected at Durang-o, Duraugo, 

 Mexico. 



Measurements nf Ilolosplra {Liostemiiui) durangoensis. 



" Type. 



HOLOSPIRA (LIOSTEMMA) YUCATANENSIS, new species. 



Plate III, lig. 2. 



Shell cylindric-conic, having the greatest diameter at the whorl next 

 to the termination of the terminal cone, with the cylindrical portion 

 gently tapering toward the base, flesh colored, with horn-brown apex. 

 Nuclear whorls two, well rounded, shining, very minutely granulose. 

 AVhorls of the evenl}^ tapering terminal cone moderately rounded, 

 early one crossed by regular, well marked, oblique riblets, which grad- 

 uall}^ decrease in strength on the later whorls, and become quite obso- 

 lete on the somewhat flattened turns of the C3dindrical part of the 

 spire, which are marked by irregular lines of growth only. On the 

 narrow penultimate whorl the riblets are again present, forming slen- 

 der curved white threads, which are about one-third as wide as the 

 spaces between them, and extend prominently over the angulated 

 periphery and short, rounded base into the narrow umbilical rimation. 

 Last whorl shortly free, the free portion slightl}^ angulated at the 

 junction of the parietal and outer wall, marked by the continuous rib- 

 lets, which become decidedly crowded behind the peristome. Aper- 

 ture subcircular, with decidedly expanded, broad, flat, not reflexed, 

 white peristome. Internal pillar hollow throughout, of uniform size 

 from the third to last whorl posteriori}^ to the terminal cone, where it 

 becomes somewhat enlarged. In the penultimate whorl it is less wide 

 than in the preceding volution and encircled by a moderately well 

 developed slightly submedian lamella. In the last whorl the pillar is 

 quite slender and decidedly oblique. 



There is one perfect and one broken specimen in the U. S. National 

 Museum, Cat. No. 187980, which were collected by E. W. Nelson and 

 E. A. Goldman, at Mujeres Island, Yucatan, Mexico. The perfect 

 specimen, the type, has 12 whorls and measures: Length, 18.1 mm.; 

 diameter of ninth whorl, 5.9 mm.; diameter of penultimate whorl, 

 4.9 mm. 



Proc. N. M. vol. xxxi— Of) 10 



