MAZATLAN UNIVALVES 233 



Comp. Trochus minutus, Mke. in Zeit. f. Mai. 1850, p. 172, 

 no. 31 : non Chemn. in Kust. pi. 13, f. 16 (non 15.) 

 Characteristic names being for tlie most part preoccupied in 

 tMs extensive familj^ I liave felt at liberty to call tbis beautiful 

 bttle species after a gentleman to wbose personal researches 

 we owe so much of our knowledge of the MoUusc-fauna of the 

 Atlantic, and to whose kindness in the loan of valuable books 

 and specimens I am under great obligations in the preparation 

 of the present work. 



Shell somewhat resembling a variety of Trochus Antonii, 

 Koch, in Phil. Ahhild. p. 2, pi. 1, f. 4 : which however has a 

 few granular rows much larger than the rest, which are ex- 

 tremely fine and far apart. The whole upper surface in T. 

 Mac-Andreffl is covered with large tubercles. The base in 

 T. Antonii is sculptured like the rest of the shell ; and the 

 columella has a smooth scooped-out surface, which is wanting 

 in this species. The Mazatlan specimen, perhaps immature, 

 has 7 whirls. Loitg. '33, lat. ■34, div. 70°. The variety from 

 Panama has 9 whirls, measuring "55 by "43. div. 60". 



BaS.— Mazatlan ; 1 perfect sp. and fragments ; L'pool Col. — 

 Panama, 1 sp. T. Bridges, Mus. Cuming. 



Tablet 1129 contains the specimen. 



Genus OMPHALIUS, Phil. 



Zeit.f. Mai. 1847, p. 21 -.—mmdh. Conch, p. 210. 



Omphalius + Chlorostoma, S. ^ A. Ad. Gen. i. 428,429:— 



Mon. in Proc. Zool. Soc. 1851, p. 180. 

 Trochus, pars, auct. Shell with a spiral ridge surrounding the 



umbilicus, ending in one or more tubercles on the columella. 



291. Omphalius ? EUGosus, var. eufotinctus. 



.PChlorostoma rugosum, A. Ad. in Proc. Zool. Soc. 1851, p. 182. 

 no. 26. 



O. frugosus, t. olivaceo-fuscd, rufo seu rufo-purpureo plus 

 miiiusve tinctd ; testa jtiniwe sulcis spiralihus suhohsoletis, 

 pauciorihus, radiatim prope suturam hand impressam rugoso- 

 plicatd ; lahro ad margincm oUvaceo, rarissime aurantio tincto ; 

 hasi sulcis crehriorihiis ; testa adidta scppis.iime detrita. 



The C. rugosum was described from an unknown localitj'. 

 It appears in Mus. Cuming as from China, but without au- 



