210 AMERICAN JOURNAL 



little more tumid ; mouth vertically narrow, the lips obtusely 

 thickened, the inner wall with a thin callosity ; umbilicus large, 

 funnel-shaped, showing five and a half whorls. 



Height 0.14, etc., in hundredths of an English inch. 



Remarks. — This very curious little shell was found by Dr. L. G. 

 Yates, about 100 feet within the mouth of the limestone cave at 

 Cave City, Calaveras Co., Cal., about 3000 feet above the sea, 

 in July, 1868. He discovered only two perfect and three im- 

 perfect specimens, being able to make only a very brief search, and 

 none were alive, though two were fresh. It would have been 

 supposed to be a Planorbis if found near water, and if the 

 streams of that country had not been thoroughly searched by 

 many collectors. It resembles Planorbis in the inverted spire, 

 and in the partial enclosure of each whorl in the next larger, 

 so that the spire shows only a small proportion to the whole 

 shell. The consequent vertical narrowing of the aperture and 

 indeed of the whole interior, is also found in some species of 

 Planorbis, but not in any American Helicoid. Indeed it is in- 

 consistent with the characters of "Helix" as defined by Lam- 

 arck, and this shell could not therefore be embraced in that 

 most comprehensive genus. The resemblance to an Ammonite is 

 conspicuous in a lateral view. It probably belongs to Helicellidce, 

 notwithstanding its thickened labrum, which we find also in H.f 

 jwlygyrella, Gast. interna and some other species. Though 

 toothless, it is apparently nearly allied to the former, in which the 

 spire is flat and of 7 to 8 whorls. It also shows affinity to Macro- 

 cyclis in the oblique flattening of the outer whorls and its strong 

 deflection near the mouth. 



It is hoped that we may soon obtain living specimens, through 

 a gentleman about to visit the cave. 



Dr. Yates also found PL. Mormonum alive at the " Big Trees," 

 4700 feet alt., the highest locality at which it has been found, 

 and on a line with the upper belt of limestone of the Sierra, 

 though that rock has not yet been detected in the grove. 



