46 



BITHYNIA. 



BITHYl^IA, Leach. 



[Animal with a small lobe on one side of the neck. Operculum 

 shelly on the inner surface, nucleus subcenti'al. Shell turbinate, 

 covered with a horny epidermis ; spire produced, whirls rounded ; 

 peristome continuous, thickened internally. The 

 Fig. 79. female is oviparous, and deposits her eggs in a 



band, attached to stones, or to the stems of aqua- 

 tic plants ; when she desires to deposit the ova 

 she seeks some smooth place and clears the sur- 

 face with her mouth before commencing ; the 

 young are hatched in three or four weeks, and 

 attain their full growth in the second year. — H. 

 & A. Ad.'] 



Fig. 80. Bitliyuia iiliclea, Lea — Shell obtusely turreted, solid, 

 A horn color, smooth; sutures impressed; whirls 5; aperture 



( /^ white, oval. 



\fy Wahlamat, near its junction with the Columbia River. Prof. 



Pal. nudea. Nuttall. My cabinet. Cabinet of Prof. Nuttall. Diameter .2, 

 length .4 inch. 

 This is a small, solid species, and is more oblique than P. decisa, Say. 

 Like it, the apex is usually cut off. Round the mouth there is a black 

 border, which contrasts with the pale horn colored epidermis. (Lea.) 

 Paludina nucha, Lea, Tr. Am. Phil. Soc. VI, 91, pi. xxiii, f. 103. 



The above is Mr. Lea's description of this species. Fig. 80 is 

 a fac-simile of the outline of his figure. I place the species in 

 this genus on the authority of Carpenter, Br. Ass. Rep. ISSt, 326. 



Fig. 81. Bitliynia seilliiialis, Hinds— Shell obtusely turret- 



ed, solid, horn colored, smooth; apex eroded; whirls 4; aper- 

 ture bluish, expanded. 



River Sacramento, California. 



Distinguished from P. nucha, Lea, which is from a neigh- 

 boring locality, by its somewhat smaller size, bluish instead 

 of white mouth, having one whirl less, the aperture more 

 expanded, and absence of the black lines round the mouth, which when 

 present is so good a character in his shell, but which, in any numerous 

 specimens of it, I do not find at all constant, and usually only to be seen 



