158 PROCEEDINGS OF THE NATIONAL MUSEUM Vol.89 



by low, lamellar, somewhat wavy, retractively slanting axial ribs, 

 which increase in numbers on succeeding turns. These ribs become 

 broadly expanded at the summit, where they form auricles which, 

 when broken, prove to be hollow. The spiral sculpture consists of 

 poorly developed threads, wliich render the riblets slightly wavy. 

 Suture strongly constricted. Periphery somewhat inflated, well 

 rounded. Base slightly mflated, well rounded, and marked by the 

 continuation of the axial ribs and by spiral threads; of the latter, 

 those adjacent to the umbilicus and those on the umbilical wall are 

 much stronger than those on the spire. The last whorl is solute for 

 about half a turn and is decidedly deflected, showing the continu- 

 ation of the axial riblets on the outside of the parietal waU. The 

 siphon, which begins at the posterior angle a little behind the peristome, 

 is deflected over the parietal wall and into the umbilicus, which it 

 plugs completely. Aperture broadly oval, oblique; peristome double, 

 the inner moderately strongly exserted and slightly reflected ; the outer 

 of almost the same width all around, marked by concentric lines of 

 growth. Operculum rhytidopomid. 



This species comes from the Isle of Pines and from the mainland of 

 Cuba about Rosario, Ensenada de Cochinos. In the Isle of Pines 

 it breaks up into several races that occupy the distinct limestone 

 ranges. The following key and brief descriptions wiU help to differ- 

 entiate them: 



KEY TO THE SUBSPECIES OF RHYTIDOPOMA PINENSE 



Shell large and stout rosarioense 



Shell not large or stout. 



Spiral umbilical cords few, strong colorabense 



Spiral umbilical cords many and weak. 



Axial ribs closely spaced ergastulum 



Axial ribs not closely spaced pinense 



RHYTIDOPOMA PINENSE ROSARIOENSE, new subspecies 



Plate 11, Figure 14 



This race comes from the south coast of Cuba, at Rosario, east sidt 

 of Ensenada de Cochinos, Santa Clara Province. We do not consider 

 the characters that distinguish it from the Isle of Pines forms sufficient 

 to constitute specific separation. It is distinguished easily from the 

 Isle of Pines forms, however, by its much larger size and stouter 

 outline. 



The type, U.S.N.M. No. 355583, has 78 axial ribs on the first of the 

 remaining turns and 104 on the last; it has 3.7 whorls remaining and 

 measures: Length, 12.2 mm.; greater diameter, 6.8 mm.; lesser di- 

 ameter, 5.6 mm. 



