APPENDIX TO YIYIPARID.E. 



Y. contectoides is distributed over a wide extent of terri- 

 tory. It inhabits the rivers of Illinois and Indiana. Spec- 

 imens from Illinois have been successfully colonized in 

 New York. Yery fine specimens of the species are found 

 in Othcalooga Creek, Georgia. A variety of this species 

 occurring in Florida, has received the name Y. Waltoni, 

 Tryon. 



Tulotoma bimonilifera, Lea, (magnifica, Conrad,) is ad- 

 mitted by the Academy of Natural Sciences to take prece- 

 dence over magnifica. T. Goosaensis, hitherto regarded as 

 a true Vivipara, is unquestionably a Tulotoma, and is well 

 characterized as such by its opercle. Perfect specimens 

 are characterized by numerous short, hairy prolongations 

 of the epidermis on a considerable portion of the surface, 

 and more particularly by a bristly fringe to the margin of 

 the aperture. 



Melantho ponderosus, Say, which occurs in the Ohio 

 river, and some of its larger tributaries, and attains a large 

 size in some portions of the Tennessee river, has also been 

 found in Mississippi and Georgia, as well as in the rivers 

 of Alabama. Mr. Tryon separates the Alabama shells 

 under the name M. Nolani. A number of years ago, Mr. 

 Lea described Paludina coardata and P. incrassata from 

 the Coosa river. From a careful comparison of numerous 

 specimens of Melantho from the Coosa with shells from 

 other regions and with Mr. Lea's unpublished figure of 

 coardata, it is inferred that coarctata and incrassata are 

 identical with the shells Mr. Tryon calls Nolani. It may 

 seem improbable that a species can exhibit so much vari- 

 ation in form in one locality ; but it is apparently an unde- 



