OXYSTYLA, MEXICO, ETC. 115 



xvii, 1894, p. 162. BALL, N. A. Fauna no. 14, p. 11. ? BLAND in 

 Grayson, Proc. Bost. Soc. Nat. Hist, xiv. p. 303 (1872), specimens 

 from Socorro I. ? SEMPER, Reisen im Archip. Phil., Landmoll., 

 p. 248, pi. 15, f. 9 (genitalia). 



The type locality is Conchagua, in the republic of Salvador. In 

 its typical development, this species is distinguished by its rather 

 broad, full form, and the series of wide, squarish or angulated, dark 

 blotches above the periphery, branching upward and below (figs. 1, 

 5, 6). The surface is smooth to the eye, black varices are wanting 

 or few one or two on the whole shell and spiral bands, conspicuous 

 in the young, are lacking in adult shells, this being the main differ- 

 ence between princeps and ferussaci. 



The most slender specimen I have seen is shown in pi. 16, fig. 5. 

 The characteristic pattern of typical princeps passes by imperceptible 

 degrees into that shown in fig. 8 of pi. 16, and fig. 10 of pi. 17, in 

 which the blotches of the median third of the whorl are split, the 

 surface of the last whorl divided into four subequal zones by three 

 series of arrow -spots, or three belts of angulation of the stripes. It 

 sometimes becomes difficult or impossible to separate such examples 

 from 0. ferussaci, which is merely a less developed or retarded race. 



Bland referred specimens of an Oxystyla, collected on Socorro Is- 

 land by Col. Grayson, to Orthalicus undatus Brug. Probably it is 

 0. princeps which lives there. 



Var. trifracta n. var. PI. 17, figs. 10, 11. 



Contour typical and sculpture well developed ; ground-color pale 

 above, becoming decidedly yellow on the last whorl, with numerous 

 dusky stripes thrice broken by girdles of angle-spots, and partially 

 obsolete below the lowest girdle ; spire with broad stripes and two 

 continuous or subcontinuous bands, one above the middle, the other 

 above or at the suture. Apex with a dark dot. 



Alt. 50, diam. 32, longest axis of aperture 30 mill. 



Alt. 53, diam. 33, longest axis of aperture 30J mill. 



Salvador (Swift). 



?0. princeps var. (3, FISCHER and CROSSE, Miss. Scient. Mex., 

 Moll., p. 455, pi. 18, f. 2 b. 



Specimens submitted by Robert Swift to Shuttleworth were con- 

 sidered by him a new species allied to obductus, according to a MS. 

 note on the label of the type. 



