278 



UROCOPTIS, S. G. GONGYLOSTOMA. 



the penult, whorl usually widest, above which it tapers regu- 

 larly, the upper part being much attenuated; the smooth 

 apical whorls being a little swollen when retained. Thin, 

 typically whitish corneous, but varying to golden brown; 

 surface lustreless, sculptured with nearly straight lamellar 

 ribs, parted by smooth intervals 4 or 5 times their width. 

 Whorls very convex, the latter half of the last one free, de- 

 scending and projecting, cylindric. Aperture slightly ob- 

 lique, nearly circular, the peristome white, broadly reflexed. 

 Axis slender, encircled by a low spiral cord. 



Length 12.3, diani. 2.2 mm. ; whorls 17. 



Length 8.7, diam. 1.7 mm. ; whorls 15. 



Western Cuba: Lomas de Candela, Guines (Poey) ; Sabana 

 de Robles (Arango), both in Havana province. 



Cyl. plicata POEY, Mem. ii, p. 31, no. 25, pi. 2, f. 9, 10 

 (1857). PPR., Malak. Bl. 1856, p. 225; Monogr., iv, p. 709; 

 vi, p. 388. ARANGO, Contrib., p. 127. SOWERBY, C. Icon, 

 xx, pi. 12, f. 105. 



Specimens which have lost the apex, have four or five 

 whorls fewer. There is a good deal of variation in the size 

 of the shell, but the lamellar ribs and attenuate spire are 

 characteristic. Sometimes some spiral threads traverse the 

 intervals between the ribs. U. scalarina has a more strongly 

 sculptured shell than plicata, and U. blainiana differs by its 

 larger size, less attenuate spire and dark color. In my opinion 

 U. plicata should be ranked as a variety of U. philippiana, 

 from which the more distant riblets alone distinguish it; but 

 the differences between the two seem to be covered by inter- 

 mediate forms in the series before me. 



The radula is long and narrow with 7.2.1.2.7 teeth, two or 

 three outer ones on each side with merely a low ledge in place 

 of cusps. The third tooth is abruptly smaller than the second 

 (pi. 43, fig. 4). 



Gundlach found U. plicata at Santiago, the specimens being 

 quite like those from Guines (see Mai. Blatter v, p. 186). I 

 think they must have been accidentally introduced there. 



U. bahamensis may be a colony of this species, imported to 

 New Providence within the historic period, and slightly 

 changed by the new environment of a low islet. 



