72 THE NAUTILUS. 
sect larvze and their cases had in many instances formed a thick 
mass over the entire surface of the shell, completely closing the 
aperture, thus causing the animal within to die. Scarcely a 
living individual could be found that was not more or less in- 
fested in this manner. 
Burr-oak trees stand near the margin of the water, and the 
acorns which had fallen from them in the water were often 
brought out with my little hand-dredge together with cockle- 
burrs, in company with the infested shells. The cockle-burrs 
were often difficult to distinguish from some of the shells, 
covered as they were with the larvee cases. 
When closely observed, I noticed that the majority of the 
dead shells were lying on the bottom of the pond with aperture 
up; some could be seen lying in this manner with but a slight 
opening remaining in the aperture, in which I could see the yet 
living animal struggling for freedom. 
A few living ones were to be found on the vegetation grow- 
ing in the water which were in all stages of infection. 
I revisited the pond in the fall, after the warm weather, and 
found a few living shells and plenty of recently dead ones; but 
scarcely a vestige of the insect cases was to be seen anywhere, 
thus showing that they flourish during the hot weather and 
after maturing the cases soon decayed, leaving no trace of the 
perpetrator that so rapidly devastated the colony.—T. VAN 
HyYNING. 
PoLyGyRA PLANA BAHAMENSIs Van. n. var.—This variety is 
distinguished from the typical P. plana (Dkr.) of Bermuda by 
frequently having a spiral internal lamina as in P. cereolus car- 
penteriana (Bld.) of Florida. The surface of the spire has finer 
sculpture than P. carpenteriana (Bld.’s) and a trifle coarser than 
the typical P. plana (Dkr.). 
The types are in the collection of the Academy of Natural 
Sciences of Philadelphia, being tray number 44468, from Cur- 
rent Settlement, Eleutha, Bahama Islands, collected by Mr. C. 
J. Maynard in 1897. 
The Academy’s collection contains other specimens of this 
variety from New Providence and Inagua Islands.—E. G. 
Vanatta. 
