— 42 — 



flora varies so much in tlio course of the year that no adéquate 

 idea of its character could be obtained irom any small set of 

 samples; Conferva, Ophiocytium, Microspora, Oedogonium 

 and Trachelomonas were however found in nearly every 

 sample. 



The following members of the algal flora show an appréciable 

 development at certain times of the year or were frequently 

 found, but in small quantity, and may be described as sub- 

 dominant : 

 Chlamydomonas, spp. 

 Pandorina morum (Mùll.), Bory. 

 Eudorwa elegdns, Ehrbg. 



Gloeocystis gigas (Kiïtz.), Lagerh. [= G. ampla (Kiïtz.), 

 Rabenh.]. 

 Gloeocystis vesiculosa, Nàg. 

 Ankistrodesmus falcatus (Corda), Ralfs. 

 Microspora stagnorum (Kiitz.), Lagerh. 

 Closterium moniliferum (Bory), Ehrenb. 



« Venus, Kiitz. 



Cosmariupi obtusatum, Schmidle. 

 Thioaitesii, Ralfs. 

 reniforme (Ralfs), Areh. 

 » venustum (Bréb.), Arch. 



Staurastrum tricorne (Bréb.), Ralfs and var. ^. 

 Lyngbya versicolor (Wartm.), Gom. 

 Synedra Acus (Kiitz.), Grun. 



Ulna (NitzschJ, Ehrenb. 

 Achnanthes mimitissïma, Kiitz. 

 Navicula exilis, Kiïtz. 



hutceolaia (Ag.), Kiïtz. 

 Gomplionema acuminatum, Ehrenb. 

 constrictum, Ehrenb. 

 Phacus pleur onectes , Nitzsch. 

 Peridinium tabulât uni, Ehrenb. 



None of thèse forms show well-marked dominance, and their 

 degree of importance varies considerably in différent years. 



A considérable number of species were ahvays only scantily 

 represented in the pond, some of tliem being présent only for a 

 very limited period. Thèse are : 

 Gonium pectorale, Mùll. 

 Tetraspora gelatinosa (Vaucli.), Desv. 



