122 OXYSTYLA, MEXICO, ETC. 



O. MELANOCHEILUS ( Valenciennes). PL 18, figs. 1, 2, 3. 



Shell rather elongate-conic, with lightly convex whorls ; tawny- 

 yellow, unicolored or rarely with one or two narrow spiral bands; 

 last whorl with several narrow blackish varices ; apex white. Aper- 

 ture white inside, showing a black varix or two ; peristome slightly 

 thickened, with a rather wide black-brown border. 



Alt. 60, diam. 34, aperture 28 mill. 



Alt. 50, diam. 28, aperture 21 mill. 



N. W. Mexico: Tres Marias Islands (Forrer, Richardson); 

 Mazatlan (Reigen) ; Sierra Madre (? Tonald in Jalisco) (Xantus) ; 

 Colima (Rolle). 



Bulimus melanocheilus VALENC. in Humboldt & Bonpland's Recueil 

 d'Observ. Zool., ii, p. 246, pi. 55, f. 3 , b. (1833). 0rthalicus 

 melanochilus (Valenc.), v. MART, in Malak. Blatt. xii, pp. 45, 70 



(1865) BINNEY, Terr. Air-breath. Moll. U. S., v, p. 410, f. 287 ; 



Man. Amer. Land Shells, p. 440, f. 484. ROLLE, Nachrbl. D. M. Ges- 

 1895, p. 130 Ortalichus melanochilus v. MARTENS, Biol. Centr. 



Amer., Moll., pp. 181, 190, pi. 11, f. 6, 7, 7a (1893) Bulimus 



zebra var. e. PFR., Monogr. Helic. Vivent. ii, p. 144 Orthah'cus 

 zebra (Miill.), CARPENTER, Cat. Mazatlan Shells, pp. 176, 177. 

 BINNEY & BLAND, Land and Fresh-water Shells of N. America, i, - 

 217, f. 371, p. 215, f. 367 (jaw). Orthah'cus undatus Brug., var. 

 ? = 0. melanocheilus Val., STEARNS, Proc. U. S. Nat. Mus. xvii, 

 1894, p. 163. 



The more oblong body- whorl, obsolescence of the dark spiral bands, 

 and numerous blackish varices are the main features separating this 

 from O.ferussaci var. tricincta, which, moreover, seems to be widely 

 separated in geographic range from what has been selected as true 

 melanocheilus by Dr. von Martens. 



It should be said, also, that the selection of the Northern Mexican 

 form as the true melanocheilus is wholly arbitrary. The original 

 specimen may have been either 0. ferussaci tricincta or 0. maracai- 

 bensis imitator. As to the original locality, " Valenciennes gives 

 simply l Nouvelle Espagne,' that is to say Mexico and Central 

 America; his figure, although showing distinct bands, agrees better 

 in its more elongated form with the N. W. Mexican species than with 

 the Central American O.ferussaci, var. tricinctus." 



It is not known from what striped form of Orthalicus the north- 

 western melanocheilus arose ; but probably future collections will show 



