1896.] 



NATURAL SCIENCES OF PHILADELPHIA. 



269 



A REMARKABLE CENTRAL AMERICAN MELANIAN. 

 BY H. A. PILSBRY. 



Some months ago Dr. Wm. H. Dall sent to the writer for com- 

 parison with the series in the collection of the Academy of Natural 

 Sciences of Philadelphia, a peculiar Pachycheilus from Central 

 America which he believed to be undescribed. The specimen proved 



to be totally different from 

 anything yet made known, 

 and may be briefly charac- 

 terized as a species of the 

 Pachycheilus Icevissiinus 

 group, with the aperture 

 characters resembling the 

 genus Melanatria of Mada- 

 gascar. 



It is about equally similar 

 to P. kevissimus var. indorum 

 Morelet and P. chrysalis 

 Brot, having the short aper- 

 Pachycheilus Dalli. ture of the former, and the 



color-tone and robust growth of the latter ; but it is a stouter shell 

 in figure than either, with the last whorl decidedly more convex. 

 The operculum is like that of other species of Pachycheilus. 



Pachycheilus Dalli n. sp.^ 



Shell ovate turreted, solid, dusky olivaceous-yellowish, with more 

 or less distinct irregular and interrupted longitudinal black streaks. 

 The surface is covered by a strong cuticle, beneath which the shell 

 substance is white with livid stains ; smooth to the naked eye, but 

 showing fine, superficial growth-lines under the lens, cut by minutely 

 wavy close spirals into a microscopic granulation, most noticeable 

 near suture and base, but often almost obliterated on the body- 

 whorl. Whorls numerous, but owing to erosion but 6 or 7 remain, 

 the earlier ones nearly flat, last two or three convex. 



^See Science (n. ser.) Ill, p. 608, April 17, 1896. This is the species re- 

 corded as " Pacliycheilus walli" in Zoologischer Anzeiger, No. 502, 4 Mai, 

 1896, foot of p. 223. It is an unfortunate typographical error, not traceable to 

 the record as officially furnished by the Academy. 



