MAZATLAN UNIVALVES ; 439 
Genus LEIOSTRACA, H. & A. Ad. 
Gen. vol. i. p. 237. Shell with a slight varix on each side of 
the spire. The species in this genus and in Eulima are only 
provisionally divided ; in consequence of the small number 
of specimens, and paucity of specific characters. 
Eulima, pars, auct. 
Balcis, (Leach ms.) Gray, 1847 ; teste Woodw. 
550. Lrrostraca Preota, C. B. Ad. 
Kulima recta, C. B. Ad. Pan. Shells, no. 291, pp. 199, 317.— 
H. & A. Ad. Gen, i. 237. 
A young shell, perfect though dead, and a fragment, answer 
to the description of this shell, which from the very produced 
base and narrow mouth, as well as the “transverse striae mark- 
ing stages of growth” appears to belong to this genus. The 
Cumingian type is decidedly a Leiostraca. The Mazatlan shell 
has 6 normal whirls, and measures long. ‘105, long. spir. *068, 
lateOsa. dis, 20°: 
Habh.—Taboga, 5 sp. O. B. Adams.— Mazatlan ; extremely 
rare, on Chama; L’pool Col. 
Tablet 2021 contains the specimen. 
dol. Letostraca Psonirarta, C. B. Ad. 
HT, §& A. Ad. Gen. i. 237. 
Kulima solitaria, C. B. Ad. Pan. Shells, no. 292, pp. 199, 318. 
One nearly perfect shell and some fragments answer to the 
description of this species. It differs from L. iota, var. retexta, 
in bemeg larger, broader, flatter, with the whirls in different 
proportions. ong. (anfr. ix.) *123, long. spir. *08, lat. °046, 
div. 23°. 
Hab.—Taboga ; a solitary specimen in large Holothuria ; 
C. B. Adams.—Mazatlan ; extremely rare, on Spondylus ; 
L’ pool Col. 
Tablet 2022 contains the specimen. 
552. Lrtostraca ————, sp. ind.. (a.) 
Tablet 2023 contains a specimen intermediate between the 
supposed L. recta and L. solitaria. It appears to have been of 
