210 
FOURTEENTH REPORT. 
Planorbis bicarinatus Say, and approaching var. 
brv. 
«/ 
Planorbis campanulatus Say? 
Gampleloma decision (Say) . 
Sphaerium acuminatum (Prime). 
aroostookcnsis 
Pils 
NORTH END OF BURT LAKE. 
• 
Lymnaea stagnalis perampla Wkr. 
L. emarginata Say, var. 
P. ancillaria parkeri (Currier). 
P. bicarinatus Say. 
P. campanulatus Say? 
C. dccisum (Say). 
S. acuminatum (Prime). 
DOUGLAS LAKE. 
L. stagnalis perampla Walker. 
L. emarginata angulata (Sowerbv). 
P. ancillaria parkeri. 
P. bicarinatus portagensis Baker and P. bicarinatus percarinatus 
Walker. 
Planorbis campanulatus smithii Baker. 
C. dccisum (Say). 
>9. acuminatum (Prime). 
$. sulcatum (Lam.). 
It will be seen from this that all of these other shells in the Straits 
of Mackinac and Burt Lake are also represented, at least by varities. 
in Douglas Lake, but this is not proof that they arrived during the 
time of Lake Algonquin as Campeloma decision (Say) ; Sphacrium 
sulcatum (Lam.), are also found in the Maple River, and the other 
forms have shown their ability to migrate up similar streams, as at 
Higgins and Houghton Lakes. 
The pulmonates from Douglas Lake which are given in the above list, 
appear to be all deep water forms, and have apparently become adapted 
to breathe water instead of air. They come up into shallow water to 
breed and lay their eggs at certain times of the year. According to the 
data on hand, Lymnaea stagnalis perampla Walker seems to prefer 
to lay its eggs on weeds, especially in the mouths of the streams, and in 
the summer of 1911 came up during July; Physa ancillaria parkeri 
(Currier), on protected, marly sand shoals in very shallow water dur- 
ing the early spring; Planorbis bicarinatus portagensis Baker and 
probably P. bicarinatus percarinatus Walker in similar places in slight- 
ly deeper water at a later time; Lymnaea emarginata angulata (Sower- 
by) in the same place as Physa only in the later part of July; and 
Planorbis campanulatus smithii Baker in mucky-bottomed shoals dur- 
ing the late summer. The writer hopes to obtain more data along this 
line next summer and the above results are purely tentative. 
These shells appear to have been forced into deep water on account of 
the fact that most of the shore of Douglas Lake is of fine, shifting 
