Amnicola galbana has the same characters as the preceding 

 species, except that the shell is chalky, the labium thicker, and not 

 quite so well appressed, and the spire proportionally longer. Fossil 

 in the tertiary deposit of Sussex county, N. J. 



Amnicola Sayana, Anthony. Shell conic, more lengthened in 

 proportion than the preceding species: diaphanous, umbilicated, 

 aperture suborbicular, with but a small portion of the labium ap- 

 pressed. Rather smaller, and more slender than A. limosa. 



Melania gracilis, vel pulckella, Anthony. Shell conical, with 

 5 6 flat whirls; apex truncated, aperture pyriform, texture light, 

 color greenish-brown, with one or two light revolving bands. HAB. 

 Stark county, Ohio. Size of M. proxima, to which it bears some 

 resemblance. 



Melania approxima. Shell lengthened, conical, tapering gradual- 

 ly to the truncated apex, upper whirls carinated, aperture ovate, 

 tinted with pink; color light brown, with two dark reddish approxi- 

 mate narrow revolving lines. HAB. Tennessee. ^ inch long. 



Melania, intersita. Shell conic, plicated, with 4 convex whirls; 

 aperture elliptical, color olivaceous. Length ^ inch. HAB. Swan 

 creek, Indiana, Mrs. Say. Allied to M. comma. 



Physa globosa. Shell globose, translucent, spire very short and 

 rounded: aperture very wide, fold well marked: whirls three. 

 Length in. HAB. Nolachucky river. 



Amnicola pallida. Shell with the form and size of A. lustrica, but 

 with a less* distinct suture; umbilicated; labium very closely ap- 

 pressed to the body whirl. HAB. Middlebury, Vermont, Professor 

 Adams. 



CORRECTIONS. 



Add L. sericatus ? Zeigler, to the synonyms of L. catascopium. 



Limnea page 8, for fig. 9 read fig. 11. 



For Paludina carinata, Val., in number 2, read P. multicarinata, 

 and let Swainion's Paludina carinata become P. unicarinata, until 

 these authors can determine which has priority. 



Paludina, p. 22, note, for urcea read urceus. 



CIRCULAR. 



It is intended that this work shall embrace all our species hitherto 

 described by American and European authors; and as the geographi- 

 cal distribution is a matter of great importance, and one which has 

 not been sufficiently noted, the author will be greatly indebted to 

 those who take an interest in this subjectj if they will forward him 

 catalogues of the species, or specimens of the univalve shells found 

 in the streams with which they may be acquainted. 



Descriptions of the animals and their habits would also be very 

 useful; and for any assistance given, acknowledgments will be 

 made. 



Communications may be addressed to the author, at Marietta or 

 Columbia, Pennsylvania, or to the care of Mr. DOBSON, Phila. 



*** No copies of this work will be issued with uncoloured plates, 

 or with duplicate plates, coloured and uncoloured. 



