PLANORBIS. 201 
above blood-heat. In the same spring were 
some aquatic beetles (Dytiscus) and extensive 
growth of conferva, and swimming on the sur- 
face were two species of water birds.—W. M. 
Gabb. 
Exitra-limital. 
A. PLANORBIS FRAGILIS, Dunker. 
Plate 6, fig. 18, 14, 15. 
Shell tumid, fragile, very delicately striate, 
pale horn or amber-colored; deeply umbilicate 
above, below rather concave; whorls four, in- 
volute, on each side rounded, rapidly increas- 
ing, the upper ones spirally striated and decus- 
sated, conspicuous below, aperture large, 
spreading, oblique, kidney-shaped; lip very 
acute, with a very delicate white callus on 
the parietal wall. 
Diam. 12:5, alt. 6°5 mill. 
Near City of Mexico. 
I have never seen this species, which may 
hereafter be found in Southern, California. 
(48) 
