BIOLOGICAL RECONNOISSANCE AT FLATHEAD LAKE. 107 



Nearly an entire afternoon was spent at the outlet attempting to secura 

 a few of these two species, and the result was not very flattering. An Illi- 

 nois bog would produce a thousand for one. The most noticeable snail, 

 and the most difficult to secure, was Limnaea emarginata, a small variety. 

 The same species was found very abundantly in McDonald lake fifteen 

 miles further to the north, and is also in Swan lake across the range east. 

 In Sinyaleamin lake the shells are for the most part singly on stones in 

 the bottom where the water is shallow, or along the bank. They are 

 very light in color and very conspicuous. To secure them it is neces- 

 sary to take a boat, row slowly where the water is shallow, and when one 

 can be seen wait until the v/ater becomes smooth and either pick it oS 

 by hand if not too deep, or by some other method. As there is much 

 trouble to determine the depth of the water on such occasions the task be- 

 comes quite difficult, and the result is often a wetting. Our best suc- 

 cess was to take an insect net, and with this gently pull the shell off the 

 rock by inserting the net under the snail, thus letting the animal fall into 

 the net. Even this is slow work. The snails have the peculiar habit 

 of letting all holds go when anything touches them, falling to the bottom 

 among the pebbles, where it is very difficult to see them. An entire 

 afternoon was spent fishing for these specimens, a couple of dozen being 

 the number secured, and many getting away. It is readily seen from this 

 that a small bottle may hold the entire catch of an afternoon. Notwith- 

 standing the difficulties, the snails present many interesting points, and 

 are well worth the effort. No bivalves were seen anywhere 



By comparing these notes with the record of McDonald lake it will bo 

 seen that the snail life of the two regions is very similar. 



The butterflies noticed were not numerous. Those seen were Coliaa 

 eurytheme, Basilarchia lorquina, Vanessa milberti, and a species of Ly- 

 caena. These latter were collected in small places where the butterflies 

 seemed as close together as they could get, as many as 75 or 100 being col- 

 lected in one small space. No effort was made to make a collection 

 of moths or butterflies, attention being diverted in other directions, but 

 on account of the cold water and the limited vegetation it is not likely 

 the best place to seek such insects in quantity. 



ENTOMOSTRACA. 



Dredgings and surface catches were made during each day of the ten 

 spent at the lake. Altogether 39 vials were fllled, each representing a 

 catch. Usually the catch represented fifty strokes of the pump. It 

 was our custom to take a surface pumping, then attach ten or fifteen 

 feet of hose, afterwprds 25 feet, then 50 or 75, then 100, afterwards 

 all that could be put together, 140 feet. It was soon discovered that dur- 

 ing the day very few entomostraca were at or near the surface, though 

 they were always to be found late at night or early in the morning near 

 the surface. To seek a solution of the problem pumpings were made 

 late at night, before daylight in the morning, and during the day. It was 

 observed that light was not suited to these animals, and that as soon as 

 day dawned they sank to a depth of 25 or bO feet, remaining until dusk, 

 when they again returned. These observations were verified later in 

 McDonald lake, in Flathead lake, and Swan lake. It was found that to 



