228 



40 



penis at the posterior border of the last segment. The testis is pyriform and the 

 copulator}' organ has probably always a rather complicated structure; with regard 

 to this point I refer the reader to Weber's description. Remains of yolk almost al- 

 ways present. Two foot glands and no oil globules. 



The Diglena males have hitherto only been observed by Weber. For a long 

 time I vainly searched for them. Not till 1920, when 1 learnt that, in the sexual period, 

 the eggs were laid in the algæ carpets on the surface of ponds, was I able to detect 

 the males of three species. The males which always seem to be much rarer than 

 the females, are only met with in May; they are creeping like the females but swim- 

 ming too and with much greater speed than the females; the motion is always 

 straight; no rotating motion has been observed. I have never seen the pairing process, 

 so well described by Weber for D. catellina. 



Triphylus lacustris Ehrbg. 

 Male: Western: 1892 p. 374. 

 Western (1892 p. 374. PI. XXV fig. 5) has observed the male but only once 



and has onh' given a very insufficient description 

 and figure of it. He only says: 



"The digestive viscera are entirely wanting; their 

 space is occupied by the large sperm sac. A large penis 

 protruded behind the foot was observed. The males 

 were found swimming amongst females. Length 'bs." 



The first time 1 met with this peculiar ro- 

 tifer was in May 1898 in a little pond near Fu- 

 resø. It was very common, but I missed the 

 sexual period. The pond was then almost filled with dead leaves, branches etc., and 

 I could never find the species again. 



In later years I have often seen the animal and have visited the ponds where it 

 was common at regular intervals. In summer as well as in winter I found females 

 with resting eggs, but curiously enough 1 never succeeded in finding the males. 



Triphylus lacustris cf. Ehbrg. after Western. 



Eosphora digitata Ehrbg. 



Male: De Beauchanip 1905 p. CCXXX. 



De Beauchamp describes the male as follows. 



"Le male d'E. digiiaia est remarquable par sa dégradation beaucoup moins grande qu'elle 

 n'est habituelle chez les Rotifères; sa forme générale est absolument celle delà femelle et sa 

 taille n'est pas beaucoup inférieure (310.« contre 415 en moj'enne); son aspect est tout a fait 

 celui d'une jeune femelle, d'autant plus qu'il a conservé les amas de granulations de part et 

 d'autre de l'œil qu'elle possède à ce degré de développement. Couronne, ceneau, pied et ses 

 glandes, muscles, vessie sont exactement semblables; sur les canaux excréteurs je n'ai pu 

 compter que trois flammes vibratiles de chaque coté alors qu'il en existe quatre chez la femelle 

 comme l'a figuré Weber; mais mon obsen'ation sur le vivant n"a pas été assez prolongée pour 



