BIOLOGICAL EXAMINATION OF LAKE GEORGE 435 



larvae; for free-living animals such as mayflies, snails and scuds, and 

 for sessile hydras and rotifers. About these beds most still fishing 

 is done by the initiated. 



Other stoneworts observed by us were all found in quite shoal 

 water — less than 10 feet — and the most interesting of them was the 

 -extremely delicate and remarkably pretty Nitella batrachosperma that 

 occurred at 5 feet, on beds of yellow ripple-marked sand, and swayed 

 in passing waves with all the aspect of a bright green frog-spittle 

 This occurred sparingly but was found by us in places as wide apart 

 as the head of Northwest Bay, the south shore of Juanita Island and 

 the outlet channel below Baldwin. Two species of Chara also were 

 found in the shoals. 



In the lake bed below the level of the Nitella zone there grow two 

 peculiar and characteristic green algae. One is a "Siphon alga" 

 Dichotomosiphon that at 40 to 50 feet in depth is so abundant as to be 

 a nuisance to the lake trout fishermen: the lead bob of their trolling 

 apparatus gathers the tangled and matted threads of this plant about 

 it and brings them to the surface in slimy dripping handfuls. This 

 is what the fishermen know as "moss." Dr. Moore is publishing else- 

 where an account of this species. The other alga, a species of 

 Cladophora invades the depths where hardly any light penetrates. Its 

 minute branching sprays usually about a fourth of an inch long and of 

 very bright green color may be found sparingly, lying amid the bottom 

 sediment at almost any depth in the lake below the shoals. 



The most abundant filamentous alga of the shore is a species of 

 Tolypothrix which fairly covers submerged stones and timbers with 

 its little tufts of brownish-green swaying threads, always and every- 

 where interspersed with masses of gelatinous palmelloid forms. 

 Among the coarser waterweeds hornwort and elodea are quite scarce 

 and the fine tall-growing Potamogeton praelongus is conspicuous, 

 forming some of the most beautiful weed beds of the lake. These 

 weed beds occur mainly at depths of 10 to 15 feet. They shelter forms 

 similar to those of the Nitella beds and many additional, including two 

 interesting waterfleas, Acantholeberis curvirostris and Eurycercus 

 lamellatus. The latter is abundant enough and large enough to form 

 an important item in the diet of some of the adult game fishes of the 

 lake. 



In the plankton of the lake, diatoms of four genera were probably 

 the most important food gatherers. Asterionella, Cylotella, Tabellaria 

 and Fragillaria. Other algae less constant but occasionally abundant 

 were Anabaena, Aphanizomenon, Aphanocapsa, Botryococcus, and 

 Staurastrum. Among the cladocerans, which all season through were 

 far more abundant than copepods, Bosmina was rather common 

 throughout the season, Polyphemus became abundant for a time in 



