OP CONCHOLOGY. 241 



slightly purple. Every specimen in my possession has the 

 apex eroded, so that the number of whorls cannot be with cer- 

 tainty stated. I should suppose the number to be nine or ten. 

 Some of them are sufficiently perfect to show several upper 

 whorls with regular folds. The aperture is probably rather 

 more than one-fourth the length of the shell." 



It will noticed at once, that the shell described by Dr. Gould 

 is not adult. The striiie arc not distinctly marked in this, as 

 in the last species; for, although visible, still the surface is 

 rather smooth and polished. The ribs are not developed on 

 the last three or four whorls, but are found on several of the 

 upper ones. The color is very constant, reddish-brown, and 

 the broad black band almost always present, revolving on the 

 periphery of the last whorl, and just above the suture on the 

 spire. Within, the color is light to dark purple, exhibiting 

 the band through the whorl. 



A number of minute specimens are before me, showing the 

 initial whorls, which are very convex, and strongly plicate; 

 these whorls are always subsequently lost by erosion. 



Mr. Eeeve's figure and description of G. Shastaensis repre- 

 sent G. occata, Hinds. 



5. GoNioBAsis Bairdiana, Lea. — t. 24, f. 10. 



Description. — Shell folded, somewhat drawn out, dark brown, 

 rather thick, single banded; whorls subattenuate, sharp- 

 pointed; suture impressed; whorls eight, slightly convex ; ap- 

 erture rather small, ovately rhomboidal, whitish within, and 

 single-banded; outer lip sharp, scarcely sinuous; columella 

 bent in, somewhat thickened and very much twisted. 



Habitat. — Columbia Eiver at Fort George, Oregon. J. 

 Drayton. 



Dimensions. — Diam. •26 inch, length 'QQ inch. 



Remarks. — In size, color and outline this is nearly allied to 

 Draytonii, herein described, but may at once be distinguished 

 by that species having no folds, and in being more convex in 

 the whorls. It cannot be confounded with Melania (Gonioba- 

 sis) Neivberryi (nobis,) which is shorter, more inflated, and has 

 two bands. The Bairdiana has five or six apicial whorls, fur- 

 nished with close, regular, well formed perpendicular folds. 

 The lower whorls have two or three very minute revolving 

 strige immediately below the suture, where the color is lighter. 

 There is a disposition to thickening on the inner margin of 

 the outer lip, and along this edge a little coloring of brown is 

 observable. The aperture is nearly the third of the length of 

 the shell. I have great pleasure in dedicating this interesting 



