232 MAZATLAK UNIVALVES 



Comp. Trochus eximius. Bve. Proc. Zool. Soc. 1842, p. 185. 

 (Payaua, sandy mud, 10 fm. Miis. Cuming.) 



This beautiful species is characterized in sculpture by a more 

 or less sharp angular keel, at about 3-5ths of the breadth of 

 the penultimate whirl, the whole siu"face being covered ^vith 

 very fine subgranular spiral strise ; basal periphery at a rounded 

 angle ; base with about 9 distant, nearly smooth and scarcely 

 raised stria?. Colouring variegated with ashy and light orange 

 brown, very rarely whoUy of a rufous tinge, stained about the 

 granules and on the basal lines with lustrous purplish red, also 

 with rich orange. The first whirl is depressed, smooth, round- 

 ed ; gradually passing into very coarse decussation, leaving 

 deep pits between ; these pass into three stronglj^ nodulous 

 ribs, the lower gi'adually changing into a keel, small ones 

 developing between the others, and both nodules and ribs 

 gradually subsiding into the typical state. The young shell is 

 of a uniform orange brown or reddish tinge. Wliirls 10. Veiy 

 few specimens possessed the operculiun, which is extremely 

 thin, of many whirls (15 in a shell of 9 whirls,) with very 

 delicate radiating striae, somewhat curved, and most developed 

 near the margin of each whii-1. Long. 1", lat. "92, div. 65". 



Hah. — Mazatlan ; common ; L'pool Sf Havre Coll. 



Tablet 1118 contains 4 sp. various ages. — 1119, 2 sp. extreme 

 forms, div. eC-SO". — 1120, 5 sp. shewing base and variations 

 of sculpture. — 1121, 2 sp. with hermit crabs. — 1122, 1 sp. with 

 operculum. 



Specimens shewing colour. — 1123, 4 sp. dark, variegation in 

 large pattern. — 1124, 3 do. with narrow streaks of light. — 1125, 

 3 do. nearly unifoi-m, dark. — 1126, 3 do. light and dark equal. — 

 1127, 3 do. light predominating. — 1128, 3 do. nearly uniform, 

 light. 



290. Teochus Mac-Andeeje, n. s. 



T. t. subelevatd, conicci, anfractihus convexiusculis, suturd dis- 

 tincta ; rubra, maculis palUdiorihus : liris spiral ibus nodosis 

 cinctd, in anfr. pemdt. vi. quarum inferiores ducepaullum majores 

 .mnt ; interstitiis impressis, lirulis intcrdum intercalatitihus ; 

 tuhercwlis confcrfis, rotundatis, extantibus ; peripheria vix an- 

 gulatd ; basi lirulis vi.v gramclosis, circiter xi. ornatd, inter- 

 .ftitiis latis ; columella Jiaud imculptd, parum contortd, regione 

 wmbiUcali impressd . 

 Vae. t. rnfo-fuscd, undatim pallidiore ; basi rubra. 



