44 Mighels^ and Adams^ Descriptions of 



all, by the punctate striae. Only a single specimen has been 

 found. It is in the cabinet of J. W. Mighels. 



PHYSA FRAGILIS. 



Plate IV. Fig. 12. 



P. testa tenuiasim^, oblique ovat& ; §pira brevi ; anfractibus quatuor; f^pei^ 

 tur& subovata, repand^ J labiolumido, lamina obtecto. 



Shell very thin and fragile, translucent, horn-color, obliquely 

 ovate ; whorls four ; last whorl canipanulate ; suture deeply 

 impressed at the enlargement of the last whorl ; spire usually 

 less than one, sometimes only one-fourth part of the length 

 of the shell ; labrum very thin, advanced ; labium tumid 

 with a thin, loosely adherent lamina. 



Length, ^55 inch ; greatest breadth, ,4 inch ; divergence, 90 

 degrees. 



Animal of a very obscure, light green color ; whole surface 

 of the body covered with oblong dark spots ; foot shorter than 

 the shell, lanceolate ; tentacles nearly white, rather long, very 

 slender ; mouth blood-red. Its motions are exceedingly rapid ; 

 very timid, withdrawing itself on the least alarm. It is very 

 tenacious of life, at least it is not easily starved. Three spe- 

 cimens are now before us in a tumbler of water, November 

 10th, where they have remained since the first of July. The 

 water has not been changed more than half a dozen times, 

 yet they are as brisk as when first taken ; and, moreover, they 

 have grown at least one quarter ; exuviae white, abundant, 

 vermicular. 



Cabinets of Bost. Soc. Nat. Hist,, Amherst and Middlebury 

 Colleges, Mons. Largillier, S. S. Haldeman, J. W. Mighels, 

 and C. B. Adams. 



Habitat. Monmouth, Maine ; discovered in a mill-pond 

 after the water was drawn off, by Mr. N. T. True, to whom 

 we are indebted for specimens. 



Remarks. This species is distinguished from P. heterbs^ 

 tro'pha by the campanulate aperture, which is constant, shorter 

 spire, tumid labium, and by its remarkable tenuity. 



