112 BULLETIN UNIVERSITY OF MONTANA 
fishing and beautiful scenery. There is no drift around the shores, most 
of the drift having lodged in the outlet. Here there is a quite a jam. 
CONCHOLOGY OF McDONALD LAKE. 
Search was made daily for shells. In the waters there were large 
numbers of a new variety of Limnaea emarginata Say, described in Nau- 
tilus, Vol. XV,* as var. montana. This is the same shell that was pre- 
viously taken in Sinyaleamin lake with so much labor, and was much 
more aboundant in McDonald like than in Sinyaleamin. Along the 
rocks in the middle of the lake they were taken in considerable numbers, 
and at the outlet others were taken among the grass and weeds in thea 
shallow water. This species seems to relate emarginata to stagnalis, 
some of the shells showing the malleations of stagnalis quite 
plainly. Placed side by side they have many points in common, 
put are very much smaller than the variety appressa of stagnalis taken 
in western Montana. 
Physa ampullacea Gld. was found sparingly, not so abundant as in 
Sinyaleamin lake. Strange to say, not a single specimen of Planorbis 
was seen. Planorbis seems to be a warm water species, and while a few 
were taken at Sinyaleamin lake, they were very scarce, and the few 
taken were small and badly broken. In the small ponds and lakes in the 
valley to the west of the Mission range Planorbis trivolvis is exceedingly 
abundant, and in the small lakes or ponds of glacial origin along Flat- 
head lake these shells are found in great numbers. 
Among the underbrush at the lower end of the lake Pyramidula stri- 
gosa var. Cooperi was found in large numbers, as also P. Solitaria Say. 
These two species have been considered distinct heretofore. A large 
series of several hundred was assorted with the attempt to make two 
species. The most widely different were easily separated, but by this 
process of elimination those remaining were more and more difficult 
to place in one species or the other, and the last remaining could appar- 
ently go as easily in one pile as the other. From external appearances 
it seems difficult to distinguish some of those found at this lake as be- 
longing to either the one or the other species. The two were found in 
the same locality, were picked up together, and were placed in the same 
receptacle. It was impossible to do anything toward working out life | 
histories, and internal anatomy may reveal differences that external 
anatomy does not disclose. But as descriptions of shells are largely 
based on external anatomy it is doubtful if these two species are distinct. 
It may be well to note here that all the shells taken so far at the upper 
end of Flathead lake are var. cooperi, none having been taken that could 
be called solitaria. 
Having found a very small variety of the shell Pyramidula strigosa, 
called alpina, at high altitude on Sinyaleamin mountain, it was thought 
the same shell might be found on the heights of McDonald peak. A short 
description of the trip in search for this shell is given in the succeeding 
pages. Sinyaleamin mountain is almost due south of McDonald peak, 
in the same range, the distance between the two peaks in air line being 
* Nautilus, Vol. XV., p. 111. 
