4A0 MAZATLAN UNIVALVES 
a brownish white. Ina genus the species of which present so 
few peculiarities, it is not thought prudent to describe it. It 
seems to have nine whirls, and measures long. °115, long. spir. 
075, lat. °045, div. 23°. 
Hab.—Mazatlan; 1 sp. off Spondylus ; L’pool Col. 
553. ? Lerostraca ————,, sp. ind. (b.) 
Tablet 2024 contains a short stumpy shell; with the apex 
decollated. It appears to have been brown, and displays a 
continuous, peritreme. It bears some resemblance to the 
W. Indian L. fulvocincta, C. B. Ad. Contr. Conch. no. 7, p. 111. 
It has four whirls, and measures ‘077 by °035. 
Hab—Mazatlan ; 1 sp. off Spondylus ; LZ’pool Col. 
554, LEIOSTRACA LINEARIS, 2. s. 
LT. t. minima, gracillind, albé ; axt recti; apice acuta; 
anfr. 1x., primo decliviore 3 nitente, vix varicosd ; apertura 
pyriformi, continua ; labio rimulam umbilicalem formante ; 
columella haud callosd. 
Distinguished by its minute size, and extremely slender 
5 y : 
growth. The habit is that of Leiostraca, though the varices 
can searcely be traced. Long. ‘072, long. spir. ‘*0d, lat. * 022, 
div. 15°. 
Hab.—Mazatlan; 1 sp. off Spondylus ; L’pool Col. 
Tablet 2025 contains the specimen. 
& 
555. LEIOSTRACA PIOTA, var. RETEXTA. 
Comp. Eulima iota, C. B. Ad. Pan. Shells, no. 290, pp. 198, 
317.—Sow. Thes. Conch. m loco.—H. & A. Ad. Gen. 1. 236. 
LL. 2iota, axt recta. 
The form above indicated accords somewhat better with 
the Panama species than with the British, but is entirely 
without twist. The British specimens are also sometimes 
straight. The shells in this genus afford so very few distinctive 
characters that no species can be certainly established without 
an accurate knowledge of the animals. The only two specimens 
