SPIROSTEMMA. 295 



13. S. TENELLA (C. B. Adams). PL 37, figs. 88-91. 



Shell slender, cylindric-fusiform, widest at or above the 

 middle, tapering towards the summit, and slightly so to the 

 last whorl; pale brownish corneous, thin, and slightly trans- 

 lucent, or red-brown and opaque. Surface glossy, obliquely 

 striate, the striae obtuse and not so wide as their intervals. 

 Whorls usually 11 to 13, almost flat, the suture margined 

 above ; last whorl strongly carinate below, the basal area small. 

 Aperture very oblique, ovate-rounded, narrower below ; peris- 

 tome white, narrowly expanded and subreflexed, the upper 

 margin adnate to the preceding whorl, or shortly built 

 forward. Internal pillar forming a wide, open spiral, cork- 

 screw-like, in the last two or three whorls, upwards becoming 

 progressively less twisted. Looking in the aperture from 

 the base, a wide false umbilicus, about one-third the diam. 

 of the shell, may be seen. (fig. 91). 



Length 12, diam. 2 mm. ; whorls 13. 



Length 11, diam. 2 mm. ; whorls 11%. 



Length 10.3, diam. 1.8 mm.; whorls 11 (Troy). 



Length 11.5, diam. 2.5 mm.; whorls 11 ) /T .,,, ,-,. N 

 Li in j- r i i n > (Little River). 



Length 10, diam. 2.5 mm.; whorls 9 j v 



Length 12.5, diam. 2 mm.; whorls 11% (W. of Ocho Rios). 



Jamaica: Troy, in St. Elizabeth Parish (P. W. Jarvis) ; 

 Bogwalk, St. Catherine; west of Ocho Rios and St. Ann's, St. 

 Ann; Falmouth, (Henderson), and Claremont (Jarvis), in 

 Trelawny; Montego Bay and Little River, St. James (Hen- 

 derson and Simpson) . 



Cyl. tenella CBA., Contrib. to Conch, no. 2, p. 23 (Oct. 

 1849). PFR., Monogr., iii, p. 580; Conchyl. Cab. p. 68, pi. 8, 

 f. 13-15 (C. tenelle). SOWERBY, Conch. Icon, xx, pi. 11, f. 

 101. BLAND, Ann. Lye. N. H. of N. Y. vi, p. 150. HENDER- 

 SON, Nautilus viii, p. 19, no. 97. GLOYNE, J. de Conchyl. 

 1875, p. 122. (Deny, in northern Manchester). Cyl. tenera 

 C.B.A., I. c. 



A widely distributed species in central and northern 

 Jamaica. It varies a good deal in color, striation and size, 

 some shells, as at Troy, being corneous and glossy, while at 

 most places on the northern coast the shells are ' red-brown 

 and more strongly striate. 



