922 The American Naturalist. [November, 
TABLE OF MEASUREMENTS OF AMPULLARIA DEPRESSA. 
Dimensions in Millimetres, 25 equal 1 inch. 
LOCALITY. Height. | Diameter. Remarks. 
Orange Mound 80 80 Largest specimen on record. 
Buffalo Bluff. 75 i bin 
Largest in collection Phila. 
A 
Recent Specimen......... | 55 58 cad. Nat. Sciences. 
TABLE OF DIMENSIONS OF PALUDINA GEORGIANA. 
; Height of 
LOCALITY. Height. | Diameter. Aperture. Remarks. 
50 33 26 Largest specimen seen, 
Mound on.......... 40 27 Average from 25 meas. 
Hitchen’s Creek... 45 24 18 \ Elongated specimens. 
42 25 15 (Variety Altior). 
Recent Specimens... 30 23 17 Largest of 200 seen. 
Hitchen’s Creek....... 27 20 15 Average size. 
: Largest recent specimen 
Recent Specimens...) 33 25 in collection of Phila. 
Acad. Nat. Sciences, 
It will be noted that the aperture of the shell, in specimens 
from the mound, measures from one-half to about one-third 
the length of the shell; but in recent specimens, from the 
adjacent creek, it is in every case over one-half the shell’s 
length. No living specimens on record attain the size of the 
average shells of some of the mounds, as will be seen by the 
figures in the first column. 
