— 45 - 



Kûtzingii) on the other hand was fourni at a point almost 

 opposite aear the S.E. bank. Such a localisation of definite 

 algal l'onus year for year at certain points in a pond, we hâve 

 noticed also in other small pièces of water; it would be interes- 

 ting to détermine the causes of this localisation. 



Afewwords may beaddedon the faunaof the pond. During 

 the early spring the chief feature is the large number of water- 

 fleas (Daphnia puleœ), which frequently occur in such quanti- 

 tés as to render the water quite turbid. In April numbers of 

 newts (both Triton cristatus and T. punctatus) are in évi- 

 dence, whilst false water boatinen (Corixa) and water soldiers 

 (Gerris) also occur. Dytiscus Nepa and Gyriurus natator 

 are occasionaily seen, whilst later especially the smaller species 

 of dragon Aies are fréquent. Vorticella is fairlv common at most 

 times of thé year, and raicroscopic worms were frequently 

 observed in the samples. 



0. — The annual cycle. 



The annual cycle is far more varied and complex than in 

 Abbot's pool. As already indicated above, we think it probable 

 that the shallow nature of the pond and its exposed position 

 (which bring a rapid and fréquent change of water-level with 

 tliem) are at least in part responsible for this. Although the 

 annual cycle lias varied appreciably during the four years we 

 hâve had the pond under observation, a careful scrutin v of the 

 data shows a gênerai séquence, which maj r be briefly tabula ted 

 as follows : 



a) Winter-phase (1) (December to February) : Microspora (2) , 

 Eunotia Arcus and epiphytic Diatoms, such as Synedra 

 radians and Eunotia lunaris. 



b) Early spring-phase (Mardi, April) : l'on ferra, Micro- 

 spora, species of Oedogonium, fllamentous Conjugatae and 

 (sometimes) Eunotia Arcus. 



c) Spring-phase (April, May, early June) : Oedogonium, 

 Spirogyra, Conferva, Mougeolia, Zygnema, Microspora. 



(Il Thèse «litl'erent phases correspond broadly to those enumerated by 

 Comère (Comère, 1906, p. 394); a = «période hyèmale»; h =« première 

 période vernale » ; c= « deuxième période verDale »: d and e= «période 

 estivale »; t /and^ 1 = « période autumnale. » 



(i 1 ! The gênera arementioned approximately in orderof importance. 



