420 THE CHICAGO ACADEMY OF SCIENCES. 
them from their rocky support, but is strong enough to carry away 
muddy sediment brought from the thoroughfares. The colonies in 
Square Lake live on a shore sheltered form the surf of the strong and 
most prevailing (northwest) winds and always in a location where the 
bottom is rocky, or sandy with stones. They are more frequently 
found in the vicinity of an inlet or thoroughfare.” (Nylander). 
Remarks: In 18438, Mighels described and figured a large 
Lymnea found in Second Eagle Lake on Fish River, Aroostook Co., 
Maine, as Limnea ampla. The shells were secured by Mr. Alexander 
W. Longfellow (a brother of the poet Longfellow) who obtained four 
specimens although he reported them as very common on the shores 
of the lake. Prof. Edward S. Morse and Mr. John M. Gould collected 
seven dead specimens in 1852. Previously to the extensive collecting 
carried on by Mr. Olof O. Nylander of Caribou, Maine, these were 
the only notes which had been made on this species. Mr. Nylander 
has made a very complete survey of the waters of Fish River and the 
adjacent lakes and the many excellent series obtained of this species 
has led both Dr. H. A. Pilsbry and the writer to consider mighelsi a 
variety of emarginata. 
A careful study of this magnificent material, much of it from the 
original locality, Second Eagle (or Mud) Lake (a large portion of 
which he has presented to the Academy of Natural Sciences of Phil- 
adelphia and to the Chicago Academy of Sciences), has laid at rest all 
doubts which might be entertained as to the propriety of uniting 
mighelsi with emarginata as a race. The opinion expressed by the 
author several years ago (Bull. Chicago Acad. Sci. II, No. 3) has been 
amply corroborated. The Maine specimens show a perfect gradation 
from typical emarginata to mighelsi as will be seen by comparing the 
figures on the plates. 
It is evident, however, that the name mighelsi has been made to 
cover many forms which should be included in other races of emar- 
ginata, a fact made clear by the examination of a large series from 
Wisconsin and Michigan. The race, as indicated by the original de- 
scription and figures, has a very large, elongated aperture, and a very 
wide, much depressed spire, quite different from the rounded aperture 
and generally bulbous form of the specimens from Michigan and Wis- 
consin which have been referred to mighelsi (figure 1b of Mighels 
plate is a transition form between mighelsi and emarginata). True 
mighelsi has been seen only from Aroostook County, Maine, and 
Brome Lake, Quebec. In Maine it shows a perfect gradation from the 
narrow, long spired emarginata to the wide, flat spired mighelsi. The 
