UROCOPTIS, S. G. IDIOSTEMMA. 167 



Conch., p. 247, pi. 63, f . 10-12 ; Monogr., vi, p. 382. SOWERBY, 

 Conch. Icon., xx, pi. 16, f. 144. ARANGO, Contr., p. 122. 

 CROSSE, J. de C., 1890, p. 235. Urocoptis (Idiostemma) un- 

 cata (GundL), PILS & VAN., Proc. A. N. S. Phila. 1898, p. 

 275, pi. 17, f. 10 (axis). 



Resembles U. fastigiata and U. geminata in the strong ribs, 

 but differs conspicuously in the peculiarly modified axial 

 armature. The first two whorls are delicately ribbed, as in 



flateralis. 

 . U. PERLATA (' GundL, ' Pfr.). PL 45, figs. 48, 49, 50, 51, 

 52. 

 Shell cylindric-fusif orm, the upper half tapering to a rather 

 wide truncation, thin, corneous, somewhat transparent. Sur- 

 face glossy, smooth except for a series of small white nodes, 

 strung rosary-like below the suture; and the base and last 

 third of the last whorl is sculptured with thread-like stria. 

 Whorls slightly convex, the last shortly free in front, rounded 

 below. Aperture obliquely round-oval, the peristome white, 

 narrowly reflexed. Internal column armed in the interme- 

 diate whorls with compressed hooks placed in obliquely ver- 

 tical pairs, curving towards each other, about 4 pairs in a 

 whorl (fig. 52). 



Length 12.5, diam. 3.2 mm. ; whorls 9y 2 -ll. 



Eastern Cuba : Yateras, district of Guantanamo, prov. San- 

 tiago, on stones (Gundlach) ; sugar-plantation "El Coco," 

 Sagua de Tanamo (Arango). 



Cyl. perlata GundL mss., PFR., Malak. Bl. vi, 1859, p. 97; 

 Novit, Conch., p. 459, pi. 100, f. 25-28; Monogr., vi, p. 362.- 

 ARANGO, Contrib., p. 106 SOWB., C. Icon., xx, pi. 10, f. 88. 

 CROSSE & FISCHER, J. de C., 1870, p. 12. CROSSE, J. de C., 

 1890, p. 216. 



In internal structure this species is intermediate between 

 U. uncata and U. lavigata; and' the external sculpture shows 

 the same relationship, the subsutural beads being vestigial 

 ribs, which in lavigata have wholly disappeared. 



The fact that in U. lavigata, pairs of hooks precede the 

 nodes on the pillar, indicates that the hook structure is the 



