MAZATLAN UNIVALVES 933 
Comp. Trochus minutus, Whe. in Zeit. f. Mal. 1850, p. 172, 
no. 3L: non Chemn. in Kust. pl. 13, f. 16 (non 15.) 
Characteristic names being for the most part preoccupied in 
this extensive family, I have felt at liberty to call this beautiful 
little species after a gentleman to whose personal researches 
we owe so much of our knowledge of the Mollusc-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 Antoni, 
Koch, in Phil. Abbild. p. 2, pl. 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-Andree 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. Long. ‘33, lat. °34, div. 70°. The variety. from 
Panama has 9 whirls, measuring °55 by °43, div. 60°. 
Hab.—Mazatlan ; 1 perfect sp. and fragments; LZ’ pool Col.— 
Panama, 1 sp. 7. Bridges, Mus. Cuming. 
Tablet 1129 contains the specimen. 
Genus OMPHALIUS, Pail. 
Zet. f. Mal. 1847, p. 21 :—Handb. Conch. p. 210. 
Omphalius+Chlorostoma, H. & A. Ad. Gen. i. 428, 429:— 
Mon. in Proc. Zool. Soc. 1851, p. 180. 
Trochus, pars, awct. Shell with a spiral ridge surrounding the 
umbilicus, ending in one or more tubercles on the columella. 
291. OMPHALIUS ? RUGOSUS, var. RUFOTINCTUS. 
?Chlorostoma rugosum, A. Ad. in Proc. Zool. Soc. 1851, p. 182, 
no. 26. ‘ 
O. ?rugosus, t. olivaceo-fuscd, rufo seu rufo-purpureo plus 
: ay Aa : gee ; 
minusve tincta ; testa juniore sulcis spiralibus subobsoletis, 
paucioribus, radiatim prope suturam haud impressam rugoso- 
plicata ; labro ad marginem olivaceo, rarissime aurantio tincto ; 
basi suleis crebrioribus ; testd adulté sepissime detrita. 
‘The C. rugosum was described from an unknown locality. 
It appears in Mus. Cuming as from China, but without au- 
