174 UROCOPTIS, S. G. IDIOSTEMMA. 



lations of the edge of the spiral fold are homologous with the 

 oblique plicae developed in Idiostemma. The external sculp- 

 ture of the shell is that of tiie ribbed forms of Idiostemma. 



47. U. INTERRUPTA (Gundlach). PL 46, figs. 60-64. 



Shell cylindric, the upper third or half tapering to a rather 

 wide truncation; thin; gray- white; surface lustreless, sculp- 

 tured with close, rounded hollow ribs above (generally in 

 large part broken in adult shells) , the ribs becoming weak in 

 the middle or wholly interrupted on the median whorls, per- 

 sisting only as white bosses above and below the suture, on 

 the later whorls; the intervals finely striate. Last whorl 

 rounded below, produced in a short, round, somewhat con- 

 tracted neck. Aperture obliquely oval, the peristome nar- 

 rowly reflexed. Internal axis wound round with a stout 

 lamella, rounded at the edge and milled like a coin ; it is 

 strongest in the median whorls, becoming lower and more 

 oblique above and below, obsolete in the last whorl, where the 

 axis is slender and straight. 



Length 12.3, diam 3 mm.; whorls 10y 2 . 



Length 11.5, diam. 3.3 mm.; whorls 10-13 (Pfr.). 



Length 14, diam. 3,3 mm.; whorls 11. 



Length 10.8, diam. 3 mm.; whorls 9i/o. 



Eastern Cuba: Manzanillo (type locality), Santiago de 

 Cuba and Cabo Cruz; larger specimens from Guisa (Gund- 

 lach). 



Cyl. ixterrupta Gundlach mss., PFR., Malak. Bl., iv, 1857, 

 p. 175; v, p. 44; Conchy!. Cab., p. 29, pi. 4, f. 7-9; Novit. 

 Conch., p. 248, pi. 63, f . 13-15 ; Monogr., iv, p. 705 ; vi, p. 382. 

 -ARANGO, Contrib., p. 121. SOWB., C. Icon., pi. 8, f. 71. 

 Urocoptis (Maceo} interrupta Gundl., PILS. & VAN., Proc. 

 A. N. S. Phila. 1898, p. 275, pi. 17, f. 7 (axis). 



Near U. geminata in sculpture, but distinct from all other 

 known species in the single stout axial lamella, rounded at 

 the edge, which is closely crenulate or "milled" like a coin. 

 This sculpture often extends below the median ridge, espe- 

 cially in some specimens which have the pillar calloused below 

 it, the prominent spiral in Maceo being homologous with 



