212 



Planorbis opercularis. Testa parva, valde depressa, casta- 

 nea, supra planulata ; apice depressa : subtus convexa, late 

 umbilicata, ad peripheriam marginata et obtuse carinata ; spira 

 anfr. 4, sutura bene impressa sejunctis ; apertura transversa, sub- 

 rhomboidea. Long, -l, lat. -j-V poll. Hab. Rio Sacramento, 

 Upper California. 



E-esenribles P. exacutus, Say, but is larger, less connpressed and 

 less delicate ; and tbe periphery instead of being acutely edged, 

 has a blunted keel like P. carinatus. 



Planorbis vermicularis. Testa parva, fornicata : spira pla- 

 nulata, apice depresso, anfr. 4, cylindraceis, ultimo prope aper- 

 turam deflexo ; subtus concava ; apertura perobliqua, elliptica. 

 Lai. -i, alt. yL. poll. Hah. Interior of Oregon. 



About the size and form of P. deflectus. Say, but is less de- 

 pressed, the whorls more cylindrical, and not compressed at the 

 periphery. 



M. P. Wilder was nominated for election as a member of 

 the Society, by C. K. Dillaway. 



ADDITIONS TO THE LIBRARY. 



Twenty-sixth Annual Report of New York Mercantile Library 

 Association. 8vo. pamph. 1847. From the Association. 



American Journal of Agriculture and Science, for February, 

 1 847. From the Editors. 



W. C. Redfield, on Hurricanes and Northers. 8vo. pamphlet, 

 New Haven, 1846. From the Author. 



Annals and Magazine of Natural History. No. 124 ; for Fe- 

 bruary, 1847. Courtis Fund. 



Gray's Genera of Birds. Part 34. Audubon Fund. 



Calcutta Journal of Natural History. Nos. 13, 14, 16. 8vo. 

 1843-4. Editors. 



Dana, James D., Geological Results of the Earth's Contraction 

 in consequence of cooling. 8vo. pamph. New Haven, 1847. 

 Author. 



Silliman's American Journal of Science and Arts. No. 8, 2d 

 Series. 8vo. New Haven, 1847. 



