GONIOBASIS. 



211 



97. G. plicifera, Lea. 



Melania plicifera, Lea. Philos. Trans., vi, p. 9.3, t. 23, f. 90. Obs., ii, p. 93. 



Wheatley, Cat. Shell.s, U. S., p. 20. Jay, Cat., 4th edit., p. 274. Binnet, 



Check Li^t, No. 211. Reeve, Monog. Melania, sp. 284. Cooper, Report, p. 



374. Brot, List, p. 3G. Gould, Moll. Expl. Exped., p. 143, f. 1G5. Trosciiel, 



Ai-chiv, fur Xaturgesch., ii, \>. 227. 

 Melasma plicifera, Lea, Chenu, Manuel, i, f. 2001. Adams, Genera, i, p. 300. 



Description. 



Fig. 419, Fig. 420. 



Fig. 421. 



Shell acutely turreted, rather thick, nearly black ; 

 spire full of folds ; apex truncate ; whorls some- 

 ■vvhat convex, the last being smooth above and 

 striate below ; aperture white. 



Habitat. — "Wahlamat, near its junction with the 

 Columbia River ; Prof. Nuttall. 

 Diameter, •4 of an inch; 

 length, 1-1 inches. 



Obsej'vations. — Among the 

 fine shells brought by Prof. 

 Nuttall from beyond the Rocky Mountains, was 

 this single species of Melania. It is remarkable 

 for its numerous folds, or ribs, which fill the supe- 

 rior whorls. The inferior whorl is entirely without 

 these ribs, but the inferior 2-"'-'*ion is furnished 

 Avith transverse strias. I am indebted to Prof. Nuttall for many spec- 

 imens of this .shell, all of which are more or less truncate at the apex. 

 The most perfect one, which is small, has nine whorls. — Lea. 



This is an exceedingly common and variable species, and 

 I give several figures of its most usual forms. Occasionally 

 the shell is thickly striate, with folds on the upper whorls only. 



Dr. Gould, in the Mollusca of the United States Exploring 

 Expedition says of this species : — 



" This shell seems to be subject to great variety, or else these arc 

 several allied species. The typical shell has the spire elongated, 

 pointed, and the whorls flattened, with coarse, longitudinal folds. 

 Olliers are surrounded by numerous, raised lines, and are nearly des- 

 titute of folds. A variety from Lake George (Oregon) must be very 

 corpulent. It is much decollated, and is light and thin. Whorls con- 

 vex ; aperture rounded, ovate ; lip very flcxuous, having a sinus pos- 

 teriorly, and a very deep one at the point of the columella; color pale 



