248 60 



the penis itself t\vo glandlike bodies the openings of which I have not been able to 

 see. Between the brain and testis a very large constant oilglobule, and scattered in 

 the body cavity many smaller oil globules. 



Size: Male 80 — 90//, penis alone 30/v. Size of female 120 /<. A. hypelasma is a 

 typical pondform, only rarely met with in the pelagic region of larger lakes; it is a 

 summerform, not appearing before May and with its maximum at the highest tem- 

 perature. The female as well known carries one large oblique female egg; two or 

 three small male eggs and a very large resting egg. 



During the large maxima in August, Sept. the males have appeared in my 

 vessels in great masses; even with slight magnifying powers they are easily recog- 

 nisable owing to their large penis; swimming with enormous speed and always in 

 straight lines, they seem to use the penis as a helm. 



Notholca longispina Kel. 



I have seen the male in great numbers; it was on a journey, when I was 

 only equipped with a very insufficient microscope; it resembled the males o{ Anurcea 

 and had no spines. 



N. acuminata Ehrbg. 

 Tab. XIII, fig. 7. 



Male: Description. Body elongate, very soft, hyaline without any distinct lorica 

 neither dorsally nor ventrally; without any deep longitudinal furrows, behind with 

 a large pouch of different form in the different specimens. No foot. Wheel-organ 

 vertical upon the longitudinal axis, consisting of a ciliary wreath, encircling a disc 

 carrying another interrupted row of cilia and a number of small hills, provided with 

 bunches of bristles. No alimentary canal. Brain large, with a large red eye. Neither 

 dorsal nor ventral antennæ have been detected. There is no contractile vesicle, and 

 the lateral canals I have observed are only very inconspicuous. Testis large with two 

 sorts of spermatozoa. Penis extremely long, almost as long as the animal, faintly 

 kneed, narrow, strongly tapering at apex, flexible. It is traversed by the seminal 

 ducts, which are covered with cilia and near the testis provided with two small pro- 

 stata glands. As far as I have been able to see, there is not, as in Brachionus, stif- 

 fened sides and no cup-shaped body at apex. On the other hand I here found a 

 peculiarly formed globular body hanging down from the apex. No transversal muscles 

 and only three pairs of longitudinal muscles could be observed. The whole body 

 was very opaque, containing large oil globules, especially in the posterior part. 



For a long time I have been in search of the Notholca, males. Apart from 

 A', longispina most of the other species seem to have their maxima at rather low 

 temperatures, being most common in the winter half year. In April 1921, in one of 

 the bays of the little river Susaa, near my summer laboratory, I observed that it 

 contained enormous maxima of A\ acuminata; they carried their eggs for a short 

 time, but they verv' soon dropped off and were to be found at the bottom. The next 



