MAZATLAN UNIVALVES 439 



GENUS LEIOSTEACA, ff. $ 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. LEIOSTKACA PEECTA, C. B. Ad. 



Eulima recta, C. B. Ad. Pan. Shells, no. 291, pp. 199, 317. 



H. Sf 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, 

 lat. '033, div. 20. 

 Hab. Taboga, 5 sp. C. B. Adams. Mazatlan ; extremely 



rare, on Chama ; L'pool Col. 



Tablet 2021 contains the specimen. 



551. LEIOSTEACA PSOLITAEIA, C. B. Ad. 



H. $ A. Ad. Gen. i. 237. 



Eulima 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 being larger, broader, flatter, with the whirls in different 

 proportions. Long. (anfr. ix.) '123, long. spir. *08, lat. "046, 

 div. 23. 

 Hob. Taboga ; a solitary specimen in large Holothuria ; 



C. B. Adams. Mazatlan ; extremely rare, on Spondylus ; 



L'pool Col. 



Tablet 2022 contains the specimen. 



552. LEIOSTEACA , sp. ind.. (a.) 



Tablet 2023 contains a specimen intermediate between the 

 supposed L. recta and L. solitaria. It appears to have been of 



