188 SMITHSONIAN MISCELLANEOUS COLLECTIONS [voL. 48 
free from the body, curved upward with the aperture nearly or 
quite in the plane of the surface of the spire, dilated and cup-like 
toward the aperture, the peristome continuous, expanded, and 
slightly reflected, with an obscure wave on the proximal side; sur- 
face striated with feeble lines of growth, color about that of Poly- 
gyra microdonta Deshayes, a pale horn-color or ashy brown, 
whitish on the peristome ; lumen of the whorls subrectangular before 
becoming solute; about one fourth of the last whorl contains a 
single prominent, somewhat oblique elevated lamina on the body 
side, which diminishes gradually toward each end, the distal end 
becoming obsolete about the point where the last whorl leaves the 
coil and begins to grow independently; the wave in the free por- 
tion seems to be a reminiscence of the infold in ordinary Holospiras 
but is almost evanescent ; diameter, major, 11.5; minor, 9.0; height, 
2.0; length of free portion of whorl varying from 1.0 to 3.0 mm. 
Diameter of aperture, long, 3.0; short, 2.0 mm. 
Habitat.—Alvarez Mts., San Luis Potosi, at 7,200 feet elevation ; 
Dr. Edward Palmer, of the U. S. Agricultural Dept. Type No. 
110,385, U. S. Nat. Museum. 
The remarkable feature of this animal, apart from its discoid 
form, is the manner in which the termination of the last whorl is 
freed from the rest and turned upward, as in Anostoma or Hypse- 
lostoma, so that, in crawling, the shell must be dragged on what 
would ordinarily be the upper surface; a fact which is confirmed 
by the worn condition in each case of this part of the shell. The 
aperture strongly recalls that of Urocoptis, suggesting at first 
glance that we have to do with a discoid member that family. How- 
ever, the internal lamina and the general aspect of the shell, except 
the umbilical region, are not very unlike the discoid Polygyras. 
One of the two specimens containing the animal was submitted 
to Dr. Pilsbry as the most competent expert in the anatomy of the 
Pulmonata who reports as follows: 
“The specimen was preserved in alcohol and had retreated some- 
what more than one whorl within the aperture. It was opened by 
dissolving the upper surface of the shell with acid until the body 
could be lifted out unbroken. The foot projected shortly from the 
rather thick collar of the mantle. It is short and proportioned 
about as in Holospira. The narrow lung extends somewhat more 
than half a whorl. Its surface is plain, without perceptible venation, 
except for the long pulmonary vein (p. v.). The kidney (K) is 
wedge-shaped and but slightly longer than the pericardium, exactly 
as in Holospira as figured in the Manual of Conchology, Urocoptide, 
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