MAZATLAN XJNIVALYES 441 



found vary in proportion : tlie smaller, vrith 6 normal turns, 

 measiiriag long. "06, lat. '028. 



Tlie larger „ -087, „ '033. 



Bai.— Mazatlan ; extremely rare, off Spondylus ; L'pool Col. 



Tablet 2026 contaias tlie larger specimen. 



556..Leiostbaca Pdistoeta, var. tod. 



Melania distorta, Phil. Moll. Sic. vol. i. p. 158, pi. 9, f. 10. 

 Eulima distorta, Desli. in Ziam. An. s. Vert. vol. viii. p. 454. — 



Phil. loc. cit. vol. ii. p. Vio.—Forles S{ Hani. Brit. Moll. 



vol. iii. p. 232.— CZrti-A.-, Moll. Test. Mar. Brit. p. 451. 

 Leiostraca distorta, S, Sf A. Ad. Gen. i. 236. 



L.t. " L. distortce" simillimd, sed minima; parte suturali 

 pauhdum latiore. 



The type of Leiostraca iota, C. B. Ad. erroneously labelled 

 'Jamaica' in Mus. Cuming, and very incorrectl.y figured by 

 Soil), is someTvhat broader and less bent than the Mazatlan 

 shells : in other respects it exactly accords. After repeated 

 comparison of very fresh specimens Avith the British dwarf 

 variety of L. distorta, the characters appear exactly alike, 

 except that the sutural portion, which (the shell beiug tran- 

 sparent) gives an appearance of a spiral line, is slightly nar- 

 rower in the Scarborough specimens received from Mr. Bean. 

 The same glossy deposit over the base, with the rather separate 

 parietal lip, giving in some directions of light the appearance 

 of an umbUicus, appears in each, and of the same shape. No 

 difference can be traced in the minute vertex, nor in the varices. 

 The colour in fresh specimens exactly accords. The specimens 

 in ]\Ir. M' Andrew's collection, grouped under Eu. distorta, vary 

 extremely iu size and arcuation. The Mazatlan shells are on 

 a much smaller scale, generallj' more bent, and most beautifidly 

 glossy and transparent. The same form occiu's m the West 

 Indies (B. M.). According to Deshayes {Lain. An. s. Vert. 

 vol. viii. p. 4-55, no. 8) it is found fossO. in Grignon and other 

 places. If it extends so far back in time, it is na,tiu*al that the 

 living shell should occupy a widely distributed si)ace. As 

 however the animals may be distinct, both in this and in L. iota, 

 a name is added expressive of its (for the genus) extreme 

 miiiuteness. The smallest sp. (of 3 normal whirls) measures 

 "035 by "016. A remarkably large sp. measures long. "082, 

 long. spir. '055, lat. '033, div. 18". 



