No. 588] POPULATION OF « BLANKET-ALG2E " 759 



stantly, and were generally very numerous. Masses of 

 eggs of Chironomus cayugce Johannsen were found en- 

 closed in an oval mass of gelatin anchored to some of the 

 algae, also myriads of newly-hatched, almost microscopic 

 larvae were seen, so it is reasonable to assume that, for 

 these pale pink or yellowish chironomus larvae (1-18 mm. 

 long), this environment is the normal one. A few larger 

 species, some of them blood-red, were found also. Larvae 

 of the "punkie" Ceratopogon and of the soldier-fly, Odon- 

 tomyia, were seen occasionally. Although mosquito-larvae 

 are found regularly in stagnant pools, it is surprising to 

 note that only twice were these larvae found among the 

 filaments of the floating algae. These larvae were not 

 identified. 



A few larval beetles and a few adults made infrequent 

 appearances. Undetermined Hydropoms and other dy- 

 tiscid larvae were among these. Although known as a 

 dweller among filamentous algae, the Haliplid beetle larva, 

 Peltodytes, was seen only once, its long spiny hairs 

 tangled in the vegetation. Adults of two genera of Hy- 

 drophilid beetles were identified as Helophorus and 

 Crenophilus and a few other diving-beetles were seen but 

 not identified. 



Although tadpoles, and once a young salamander, were 

 found in the collections, they can hardly be reckoned as 

 members of the society under consideration. 



Dominant Forms. — In this diverse population the con- 

 stant and abundant forms have been few. Spirogyra, 

 especially Spirogyra varians, Mougeotia and Zygnema, 

 were the principal constituents of the "blankets." 

 Among the Diatoms, the dominating forms were Cocco- 

 nema, Navicula, Gomphonema and Synedra. Other algae 

 were best represented by Closterium, Dictyosph cerium 

 and Dinobryon. Among the animals Paramecium, 

 Euglena and the rotifer, Diglena, were quite constant. 

 The forms that appeared most regularly were Cyclops 

 and the larvae of Chironomus. Some of the less constant 

 forms showed the influence of seasonal variation. 



