39 227 



A large strongly elongated testis; owing to (he extreme slenderness ol llic body a 

 copulatory organ conld not be observed; only a long ductus seminalis but not covered 

 with cilia; a bunch of cilia at the opening of the penis on the posterior border of 

 the last segment. No prostata glands observed. Six transversal muscle bands and at 

 all events three longitudinal muscles. Two pedal glands. No oil globules. Length of 

 male 250—280, but measvned without pressure most probably only 15 — 20// broad. 

 Length of female 250—280 



•8 



/"• 



It is only with some hesitation, that I have determined this species as D. (jiiajfd 

 Gosse. It was found in great quantities in a little pond, near Hellebæk, North Sea- 

 land (Time 'Vv 22). The female was characterized by a well marked neck and a 

 verj' tumid abdomen; a frontal hood, two red eyes and two long slender straight 

 toes; it was in full accordance with the figure by Hudson-Gosse (PI. XIX, fig. 9). 11 

 was extremel)' restless and variable in form. It lived in the alga coverings on the sur- 

 face of the pond; a little of this material was isolated with many hundred specimens; 

 two days later the males appeared; it was only by means of the greatest accuracy and 

 with the best possible light conditions that it was possible to detect the males which, 

 with regard to restlessness, hyalinitj' and especially slenderness, surpassed all that 

 has hitherto been observed. The eggs were laid on the carpets, i-esting eggs were not 

 observed. 



Diglena mustela Milne. 

 Male: Milne 1885 p. 188. 



According to Hudson-Gosse Suppl. p. 31, Milne has described the male: "It is 

 a much smaller animal than the female, more elongated, and with a more developed 

 hood. Its structure is normal." I have not been able to get Milne's paper. 



Diglena volvocicola Zawadovsky. 



Male: Zawadovsky 1916 p. 1. 

 Zawadovsky (1916 p. 1) has described and figured a Diglena Irom V. globator; 

 he describes the male, gives some figures of the pairing process and mentions that 

 some minutes after having been hatched the males ai-e readj' to copulate. The paper 

 is written in Russian with a very short resumé. 



General remarks. The Diglena males are characterized by being shaped al- 

 most like the females; they are only more slender than these; there does not seem 

 to be any neck; they onlj' taper posteriorly not in front and there is no frontal 

 hood. They are extremely hyaline without any lorica, but the skin is thicker in the 

 middle part of the body and thickest on the dorsal side; commonly the foot is not 

 sharply defined. The species described have all the wheel-organ formed like that of 

 the female, but it has a more vertical not a ventral position. The two eyes are vi- 

 sible; only the dorsal antenna has been observed; no mastax and only feeble rudi- 

 ments of the alimentary canal; no contractile vesicle; vibratile tags fewer in number 

 than in the female; most probably the lateral canals always open on the side of the 



