HAZATLAN UNIVALVES 233 



Comp. Trockus minutus, Wee. in Zeit. f. Mai. 1850, p. 172, 

 no. 31 : non Chemn. in Kust. pi. 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 Antonii, 

 Koch, in Phil. Abbild. 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-Andreas 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. 

 Sab. 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 :Handb. Conch, p. 210. 



Omphalius + Chlorostoma, H. Sf 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. 



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



no. 26. 



O. ?rugosus, t. olivaceo-fuscd, rufo seu rufo-purpureo plus 

 minusve tinctd ; testa juniore sulcis spiralibus subobsoletis, 

 paucioribus, radiatim prope suturam haud impressam rugoso- 

 plicatd ; labro ad marginem olivaceo, rarissime aurantio tincto ; 

 basi sulcis crebrioribus ; testa adultd scepissime detritd. 



The C. rugosum was described from an unknown locality. 

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



