44 DRYM^US, MEXICO AND CENTRAL AMERICA. 



Alt. 27, diam. 12, length of aperture 14^ mill. 



Northern Guatemala. 



Bulimus castus PFR., P. Z. S. 1846, p. 112 ; Monogr. Helic. Vi- 

 vent. ii, p. 47. REEVE, Conch. Icon, v, Bulimus^ pi. 45, fig. 282. 

 TATE, Am. Journ. Conch, v, pp. 152, 156 (1870). Bulimus 

 (Leiostracus) castus PFR. in Malak. Blatt. ii, p. 153 (1855). Otos- 

 tomus (Leiostracus) castus, H. & A. ADAMS, Gen. Rec. Moll, ii, p. 



151 Bulimulas castus v. MART., in P. Z. S. 1875, p. 68.Buli- 



mulus (Drymaiis) castus, FISCH. & CROSSE, Miss. Seient. Mex., 



Mollusca, i, p. 485, pi. 24, figs. 11, 11 a-d Otostomus castus v. 



MARTENS, Biol. Centr. Amer., p. 206, pi. 12, f. 16-21. 



Peculiarly graceful in contour, and while allied to the two species 

 preceding, yet easily distinguished by its slender form, smooth, not 

 malleated surface, fine spiral striation, and purity of coloring. 



Pfeiffer's types were whitish, with a blush toward the base and 

 aperture, the peristome roseate. Dr. von Martens offers the follow- 

 ing arrangement of varieties and variations. 



A. typicus ; Small, length 19-23, diam. 11, aperture 10-12J mill. 

 a : unicolored, white, peristome, more or less roseate. 



b: irregularly streaked with brown (Fig. 42). 



c: Three blackish- brown bands, either interrupted (Reeve, 



loc. cit. fig. 282) or continous (fig. 43, 44). 



Central .America : probably Vera Paz (Delattre var. a). N. Guat- 

 emala: Cohan (Morelet, Salvin : varr. a, b, c); Tamaliu (Sarg). 



B. xantholeucus : large, a little more inflated, length 25, diam. 



14, apert. 15 mill.); white, apex and peristome yellowish (Fig. 52, 53). 

 N. Guatemala : Sabo, in a tributary valley of the River Polochic, 



at an elevation of 3800 feet above the sea (Champion). 



C. porrectus : Elongated, more slender, length 30-35, diam. 14- 



15, apert. 18-19 mill.) 



a. Uniform white, the columella only pink (Figs. 47, 49), (Bali- 

 mulus castus var. B, Fisch. & Crosse, loc. cit. fig. 11 b.) 



b. Two or three purple-brown bands, the aperture roseate (figs. 

 45, 46). (Balimulus castus var. } , Fisch. & Crosse, loc. cit. fig. lie, d). 



c. Streaked, columella only roseate (Fig. 48.) 



N. Guatemala: Coban or Tamahu (Morelet or Sarg.: varr. a, b); 

 Vera Paz (Stoll : varr. b, c). 

 " The three varieties, A, B, C, appear to be distinct at first sight, 



