216 



LAND AND FRESH-WATER SHELLS OF N. A. [pART IV. 



pressed; whorls eight, slightly convex; aperture rather small, ovately 

 rhomboidal, whitish •within and siugle-banded ; outer lip scarcely sin- 

 uous ; columella bent in, somewhat thickened and very much twisted. 

 Habitat. — Columbia River at Fort George, Oregon ; J. Drayton. 

 Diameter, "26 ; length, '66 of an inch. 



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

 Draytonii, herein described, but may at once be distinguished by that 

 Fig. 429. species having no folds, and in being more convex in the 

 whorls. It cannot be confounded with Melania {Goniohasis) 

 Newberryii (nobis), which is shorter, more inflated, and has 

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

 nished with close, regular, well formed, perpendicular folds. 

 The lower whorls have two or three very minute, revolviug striiB 

 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 aper- 

 ture is nearly the third of the length of the shell. I have great 

 pleasure in dedicating this interesting little species to my friend, 

 Prof. Spencer F. Baird of the Smithsonian Institution, to whom I am 

 greatly indebted for many kind services, and who has done so much 

 for the advancement of the Natural Sciences of our country.— Lea. 



This species differs very much in form from the others in- 

 habiting the Pacific States. 



D. Shell angulate. 



102. G. trocliiformis, Conrad. 



Melania trocliiformis, Coxkad, New Freish-Water Shells, p. 56, t. 8, f. 11, 1834. 

 DeKay, Moll., New York, p. 100. AVueatley, Cat. Shells, JJ. S., p. 27. Binney, 

 Check List, No. 275. Brot, List, p. 31. MUller, Synopsis, p. 47. 



Description. — Shell short, conical, ventricose, turreted ; -p'lg. 430. 

 two spiral, prominent lines on each whorl, the intervening 

 spaces concave ; summit of the whorls flattened, angulated ; 

 body- whorl angular, with the periphery carinated ; base 

 flattened ; aperture small ; labrum angulated in the middle. 



Habitat. — Streams in North Alabama. 



Observations. — A species easily recognized by its strong ribs, or by 

 its sulci, and its trochiform shape. — Conrad. 



