38 PROCEEDINGS OF THE ACADEMY OP 



Viviparus multicarinatus (5.) ex Hald. 



The third section of Viviparus, or another closely related to it, perhaps in- 

 cludes V. bengalensis (Ad.) ex Lam., V. borroughianus Gill ex Lea, V. bilineatus 

 Gill, and other Indian species ; the suspicions that might be entertained as 

 to the strict affinity of species so widely separated geographically, can only be 

 relieved by an examination of the mollusks themselves ; the shells are very 

 similar. 



The genus Viviparus is represented by a number of species in the lignite 

 beds of Fort Union which have been referred by Messrs. Meek and Hayden to 

 the Eocene epoch. My friends, Messrs. Meek and Hayden, have adopted the same 

 conclusions as myself regarding the distinction of Viviparus and Melantho, and 

 have now referred, with myself, six of the species formerly described by them, to 

 Viviparus, accepting that name, and two others to Melantho. Five of those 

 species are distributable among the three groups above indicated, while the 

 sixth is the representative of a distinct one. The following list shows their 

 affinities : 



\ I- 



Viviparus Leaii M. and H. 



retusus M. and H. 

 " Conradi M. and H. 



I II. 



\ HI. 



" trochiformis M. and H. 

 " Leidyi M. and H. 



I IV. 

 Shell rather thick, with numerous revolving lines, sometimes obsolescent. 

 Viviparus Raynoldsianus M. and H. 



These species will be illustrated and fully described in the forthcoming work 

 of Meek and Hayden on the Fossils of the Upper Missouri country. 



In the beds at Fort Washington on the banks of the Potomac River, which 

 probably belong to the Post Pliocence epoch, a species of Viviparus is found in 

 great numbers, which appears to be referrible to the V. subpurpureus ; the latter 

 is now only known to exist in Florida and the Western States. Mr. L. E. Chit- 

 tenden first obtained specimens from Fort Washington ; Mr. Binney also con- 

 siders the specimens to be referrible to the V. subpurpureus. 



Group LIOPLACES. 



The rachidian teeth are broadest and angulated at the base ; narrowed above, 

 and recurved, ivith the margins entire. The inner teeth of the pleura are ob- 

 lique, oblong, recurved and entire ; the median and outer pleural teeth are also 

 entire, obliquely recurved, narrowed and terminating each in a point, or claw- 

 shaped. 



MELANTHO Bowdich. 



Shell imperforate or rimate, turreted, thick and of very compact structure, 

 never provided with colored bands, with the whorls more or less compressed 

 longitudinally, smooth or rarely carinated. Aperture obliquely semi-cordi- 

 form, rather narrow, broadly rounded and sinuous or retreating backwards 

 at the base, the outer lip trenchant, and produced near the base ; columellar 

 lip nearly straight, closely appressed to the body whorl and forming nearly a 

 right angle with the outer. 



Operculum corneous, with its elements wholly concentric. 



Melantho is a type peculiar to America, I believe. It is readily recognizable 

 by the peculiar physiognomy of the shell, produced by the compression of the 

 whorls in a longitudinal direction, so that the sides of each are nearly parallel, 

 and a turreted form is thus obtained. It may be therefore likened, as to form, 



[Feb. 



