PLANORBIS. 193 
5. PLANORBIS HALDEMANT, Dunker. 
Plate 5, fig. 10, 11. 
Shell discoidal, depressed, rather solid, pale 
horn-colored, obsoletely striate, rather concave 
both above and below, almost flat, 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 gracilentus, for the slight and 
gradual increase of diameter of the whorl 
towards the aperture is common to many spe- 
cies of Planorbis, and certainly not the char- 
acter assigned to Planorbella by Haldeman, 
“ aperture campanulate or bell-shaped.” 
(40) 
