81 269 



as I should have wished. A more thorough investigation was planned for the year 

 1922, and on ^/s 1922 shortly after the pond had thawed, the (irst sample was taken. 

 The whole year round every ten days samples were taken, and I was prepared for 

 a more thorough investigation. On 5/V the first females appeared; they were, as 

 expected, of the saccate form, but not to be distinguished from a typical A. Brightwelli, 

 the rami being without inner tooth. The species was observed during the whole of 

 May and June; it was rather rare, and no humped forms appeared. Then a period 

 of heavy showers occurred, and during the whole time from July to late in August 

 the downpour was extremelj' high; the temperature was low not above 14 — 16° C. In 

 the last part of June the species disappeared. The pond was under regular observation 

 till 29/1 when the frost appeared, and the pond was frozen over. During this time not 

 a single Asplanchna was observed in the pond. Most probably the melancholy result of 

 so many excursions was due to the bad weather. In 1921 the whole summer was very 

 dry, the temperature was above twenty degrees Celsius, and often rose to twenty-five; 

 the downpour was extremely small. Whereas in 1921 the pond teemed with flagellates, 

 often forming scum upon the surface, it was brown in 1922; of flagellates appeared 

 only Eudorina and later on Voluo.v both in relatively few numbers. The pond will 

 be under regular observation also in 1923. 



Asplanchna triophtalma Daday. 



Male: Daday 1883, p. 261. 

 V. Daday (1883, p. 261, Tab. fig. 3) gives a long description of the male un- 

 fortunately in Hungarian. 



It is furnished with a figure, which in a very high degree differs from all other figures of the 

 males of Asplanchnadœ. It is much more in accordance with the males of Brachioniis; this 

 holds good especially with regard to tlie structure of the testis and penis. The three e3'cs 

 which are stated to be one of the most cliaracteristic peculiarities in the specimen are indi- 

 cated in the figure. 



V. Daday (91, p. 84) only says: Körper cylindrisch, nacli hinten verengt, ohne F"ortsätze; 

 mit zwei Seitenaugen und einem Stirnauge. Size male 200^ — 400/«; female 800 — 1200 /(. 



Asplanchna Sylvestrii Daday. 



iMale: Rousselet 1913, p. 61. 



RoussELET (1913, p. 61, PI. 5, fig. 5 — 6) gives the following short description. 



. A. Silvestrii is mainly characterized by the double-humped form of the female. Rousselet 

 (p. 62) shortly states "that the male is humped but the side humps are not bifid. According 

 to the description it is indistinguishable from the male of A. amphora. Length of female 1150 //. 

 of male 408/«. The species is described by Daday (1902) from Chile, and later on found in 

 Devil's Lake, North Dakota; the water is brackish." 



General remarks. 

 The males of the genus Asplanchna are very little reduced; apart from the re- 

 duction of the alimentary canal they are almost constructed quite like the fenuiles. 



D. K. D. Vidensk. Selsk. Skr., nalurv. og malheni. Afd., S. Rickko, IV, 3. 3(3 



