58 PROCEEDINGS OF THE ACADEMY OF 



lines of growth, and strong, comparatively large concentric undulations, most 

 distinct and regular on the anterior slope, where there are sometimes verj 

 obscure traces of about three radiating ridges. 



Length of the largest specimea seen, 0-67 inch ; breadth of do., 0-54 inch ; 

 height, 0-35 inch. 



The specimens show some variation in their proportions, as well as in the 

 regularity and distinctness of the undulations, the largest individual from 

 which the above measurements were taken being proportionally a little wider 

 and more elevated than some of the smaller ones, while its undulations are 

 less distinctly and regularly defined. As there are various gradations, how- 

 ever, in these characters, I am at present inclined to regard them as mere in- 

 dividual modifications of one species. 



Owing to the thinness of the shell, the undulations are often quite well de- 

 fined on internal casts, particularly along the anterior slope. 



The only N. American recent species, with which I am acquainted, that ap- 

 proaches this in size, is the A. Neioberryi, described by Dr. Lea, from Califor- 

 nia. From this the species under consideration differs in having its apex 

 nearer the posterior, and much more pointed and curved backward. The 

 undulations of its anterior slopes also give the shell quite a different appear- 

 ance. 



Locality and position. Fossil Hill, Hot Spring Mountains, Idaho Territory. 



Melania (Goniobasis?) scdlptilis, Meek. 



Shell of medium size, conoid-subovate ; spire more or less elongate-coni- 

 cal, with convex slopes, the apical angle being greater in the young than in 

 the adult, not eroded at the apex; volutions six to seven, rather distinctly 

 convex; suture strongly channeled ; aperture ovate, a little oblique, rather 

 narrowly rounded below; lip sharp, most prominent below the middle, and 

 slightly sinuous at the lower inner side. Surface elegantly ornamented by 

 numerous very regularly disposed, slightly flexuous or sigmoid vertical costae, 

 which are crossed by equally distinct and regular spiral ridges, about four of 

 which may be counted on each volution of the spire (excepting those near 

 the apex, which are smooth), and eight to ten on the last turn, on the under 

 half of which they are most strongly defined; minute lines of growth may 

 also be seen by the aid of a magnifier; costie slightly nodulous at the points 

 where they are crossed by the little revolving ridges. 



Length, 0-63 inch; breadth, 0-33 in. 



This is a neat species, remarkable for its sharply defined and very regular 

 cancellated sculpturing. The vertical costae are equally well defined on all 

 the volutions excepting those near the apex and on the under side of the last 

 one, while the revolving lines or ridges become a little more distinct on the 

 lower part of the body turn. Although there are nearly always four of these 

 revolving ridges on the volutions above the last one, in a few examples as 

 many as six may be counted on these turns, but this is due to the intercala- 

 tion of a smaller one between two of the others, and the exposure of another 

 above the suture, that is usually hidden beneath it by each succeeding turn. 



Locality and position. Hot Spring Mountains, Idaho. 



Melania (Goniobasis) sdbscclptilis, Meek. 



Shell apparently not attaining a medium size ; spire conical with convex 

 slopes ; apex pointed, not eroded ; volutions about seven and a half, flattened 

 convex; suture chanueled ; aperture ovate, slightly oblique, rather abruptly 

 rounded below ; margin of lip most prominent below the middle, and faintly 

 sinuous on the lower inner side. Surface ornamented with small, regular, 

 slightly sigmoid, vertical costae, with an obscure revolving ridge just below, 

 and a slight angle above, the suture, to which prominences the costae impart 



[April, 



