40 BULLETESr 181, U1ST:TED states NATTOISPAL IVnJSEUM 



KEY TO THE SUBSPECIES OF CROCIDOPOMA (CYCLOCUBANA) PERDISTINOTUM 



Spiral cords at peristome 24 toroense 



Spiral cords at peristome 31 perdistinctum 



CROCIDOPOMA (CYCLOCUBANA) PERDISTINCTUM TOROENSE, new subspecies 



Plate 8, Figukes 10-12 



Shell planorboid. Nuclear whorls 1.5, strongly rounded, smooth. 

 Postnuclear whorls very much rounded, circular in cross section, 

 marked by strongly elevated spiral cords, which are of almost equal 

 strength and are separated by spaces about three times as wide as 

 the cords. Of these cords 9 occur between the summit and the 

 periphery and 15 upon the remainder of the shell. The axial sculpture 

 consists of incremental lines and somewhat rough resting spaces. 

 Suture very deeply openly channeled. The last whorl is solute for 

 about one-twentieth of a turn. Base very broadly openly umbilicated. 

 Operculum as described for the subgenus. 



The type, U.S.N.M. No. 355777, was collected by Gundlach at 

 Monte Toro, Guantanamo, Oriente Province. It has 4 whorls and 

 measures : Height, 4.2 mm. ; greater diameter, 10.2 mm. ; lesser diam- 

 eter, 6.9 mm. 



The lesser number of spiral cords will differentiate this from typical 

 C. {C.) perdistinctuTii perdistinctu7n (Gundlach). 



CROCIDOPOMA (CYCLOCUBANA) PERDISTINCTUM PERDISTINCTUM (Gundlach) 



Plate 8, Figubes 13-15 



1858. Cyclotus perdistinctus GrrNDLACH, Malak. Blatter, vol. 5, pp. 192-193. 



Shell small, planorboid, thin, wax colored, with a greenish tinge. 

 Nuclear whorls 1.5, well rounded, smooth, the last half turn showing 

 the merest beginning of the spiral sculpture of the succeeding turns, 

 forming a very slightly elevated apex. Postnuclear whorls circular 

 in cross section, marked by strongly elevated, slender spiral cords, 

 which increase in number with the growth of the shell by intercalation. 

 On the first postnuclear turn 4 of these cords are present on the spire ; 

 on the second, 7 between the summit and the periphery, while on the 

 last turn 31 can be counted in the circle of the peristome of the aper- 

 ture. These spiral cords vary in strength, depending upon whether 

 they represent intercalated elements or the major cord. They are 

 never so wide as the spaces that separate them and rarely wider than 

 one-half of the spaces. In addition to the spiral sculpture the shell 

 is marked by slender incremental lines, which render the free edge of 

 the cord slightly roughened. The last twentieth of a turn is solute. 

 The underside shows a broad open umbilicus more or less funnel 



