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MAZATLAN UNIVALVES 
987. UVANILLA INERMIS, Gimel. 
U. t. “U. olivacee” similliméd; sed sculptura fortiore, rugis 
in spira distantioribus ; lined granularum interna in basi vie 
monstrante ; regione umbilicali alba, cavitate profundd, caring 
spirali acuta circumeunte, extus vie excavata ; callositate tenus 
diffusa. 
Trochus inermis, Gimel. p. 3576, no. 62.— Schroet. Hini. vol. 1. 
p. 719, no. 100.—Dillw. Descr. Cat. vol. ii. p. 787, no. 67.— 
Lam. An. s. Vert. vol. iv. p. 127, no. 17.—Kien. Icon. Conch. 
pl. 14, f. 2, 2a. 
=Trochus olivaceus, Phil. in Zeit. f. Mal. 1848, p. 188: non 
Gray in Wood. 
This shell, which was brought in some abundance by Capt. 
Kellett, is not the T. olivaceus, Wood, as Phil. seems to have 
supposed. There can hardly be a doubt that it is the species 
figured by ven. and therefore, it is presumed, of Lam. 
Whether it be that of the Linnean writers, can scarcely be 
determined, when the differences are so slight. 
It exactly remembles U. olivacea in almost all respects : 
but has coarser, more distant ruge on the body of the whirls ; 
and in the umbilical region is white, more resembling U. un- 
guis. Base with the inner row of granules scarcely developed : 
umbilicus deeply scooped, covered with a thin diffused callus, 
bounded by a sharp spiral ridge, scarcely scooped outside. 
The young shell has a fine keel in the place of the inner row 
of nodules, marked off by two faint spiral grooves, on the 
medial portion. Whether it be really distinct from U. oliva- 
cea must await a knowledge of the operculum, and a compari- 
son of additional specimens. The smallest sp., of 6 whirls, 
measures long. (apex to basal wing) ‘86, lat. °98, div. 80°. 
Hab—Mazatlan ; 2 young sp. only ; L’pool Col. 
Tablet 1096 contains the youngest (most characteristic) sp 
288. UvanrILLa uneois, Mawe. 
Trochus unguis, Mawe, in Wood Ind. Test. Suppl. p. 16, no. 2, 
pl. 5.—Rve. Conch. Syst. vol. ti. p. 165, pl. 217, f. 6.—Kien. 
Icon. Conch. pl. 13, f. 1 (max.) 
Turbo unguis, Desh. in Lam. An. s. Vert. vol ix. P- Pic no. 42. 
=Turbo digitatus, Desh. Mag. de Guér, 1841, pl. 3 
= Trochus amictus, Val. Voy. Venus. 
June 1856. : Ww 
