PLANORBIS. 



193 



5. PLANORBIS HALDEMANI, Dunk^r. 



Plate 5, fig. 10, 11. 



Shell discoidal, depressed, rather solid, pale 

 horn-colored, obsoletely striate, rather concave 

 both above and below, almost fiat, pitted in 

 the middle of each side ; whorls five, oval, 

 rather involute ; aperture ovate heart-shaped, 

 somewhat dilated. 



Diameter 12-5, alt. 4 mill. 



Mexico, Lower California. 



Mr. Binney has placed this species in Pla- 

 norbella, but it surely belongs in the typical 

 group along with gracilenhts, for the shght and 

 gradual increase of diameter of the whorl 

 towards the aperture is common to many spe- 

 cies of Planorhis, and certainly not the char- 

 acter assigned to PJanorhella by Haldeman, 

 " aperture campanulate or bell-shaped." 



(40) 



