630 MINNESOTA BOTANICAL STUDIES. 



amy gdaloides individuals is about 2^-3 inches in diameter at 

 four inches from the ground, and 16 feet in height. The larg- 

 est cottonwood, No. 5, shows a horizontal spread of its top of 

 2^ feet, while a willow (S. amygdaloidcs} near it spreads its 

 branches 8 feet in a horizontal diameter. A number of trees 

 have been marked and their study as well as that of the whole 

 island is being continued. The willows are now so large that 

 for some time a flock of English sparrows regularly roost in 

 them and they seem to prefer the part of the section that is 

 flooded. 



ANIMAL LIFE OF THE ISLAND. 



Did the limits of this paper permit, an interesting chapter 

 might be added under this heading. Crayfish, voles, mice, 

 and muskrats burrow under and in the island, since the sum- 

 mer of 1898, the cottontails resort to it, and in August of 1899 

 some minks had made their home under the old ties, which 

 once formed the engineer's pontoon. Near the mink's home a 

 song-sparrow had hatched its young on a thistle bush. Some 

 of the young trees on the West section have been infested with 

 the spotted willow aphid, Mclanoxanthus saliciis,* since the 

 summer of 1899 and their secretions attract swarms of flies and 

 wasps. That the frogs are there is self-evident, but I also 

 captured a fine green tree-frog, and a bunch of prickly cater- 

 pillars of the morning-cloak butterfly, Euvanessa antiopa, found 

 their table spread on the willows. 



* Identified by Dr. Otto Lugger. 



