280 92 



and the want of contractile vesicle as highly organised. This especially holds good 

 with regard to wheel-organ, brain and sensitive organs. The lorica is well developed, 

 corresponding in composition, clefts and thorns with that of female; only it is much 

 softer in the male sex; especially the Diaschiza males seem to be very slender ani- 

 mals. The foot and toes are well-developed; the peculiar tuft of hairs characteristic 

 of the genus Diaschiza and situated upon the dorsal side of the foot, is also found 

 in the male. The wheel-organ is almost the same as that of the female, but in the 

 centre of the head there are not the projecting lips at the buccal orifice, especially 

 characteristic in Diaschiza. In the Salpina males a rudimentary alimentary canal 

 with rudiments of mastax without teeth. The two excretory canals are most pro- 

 bably always present with openings near the genital opening. The testis is large, 

 filling the greater part of the body cavity. The genital opening is on the dorsal side 

 of the foot; it is surrounded by cilia. 



Cathypnadæ. 



The family comprises three genera: Monostyla, Cathypna and Distyla. Curiously 

 enough, though some of the species f. i. Monostyla cornuta and Cathypna luna belong 

 to the most common Rotifers in ponds overgrown with vegetation, males are quite 

 unknown in this family. 



Coluridæ. 



The family comprises the two genera: Colurus and Metopidia; we only know 

 the males of Cohirus bicuspidatus, Metopidia lepadella and Metopidia solidus. 



Metopidia lepadella Ehrbg. 



Male: Gosse 1889ii, p. 106. 

 Harring 1917, p. 534. 

 Tab. V, fig. 3. 



Gosse (in Hudson-Gosse 1889ii, p. 106) thinks he has seen the male: 



"A minute creature, in form a very long cone, tapering to a point, with two slender 

 toes; in front, quite truncate, with a sharp horn projecting from its forehead. No organisation 

 was visible witliin, save two conspicuous clear vesicles, side bj' side in tlie middle of tlie 

 bodj% not at all like oil-globules, being irregularly oblong: nor accidental, being found in 

 each of a large number of individuals, seen at different times. A pair of fine lines ran far 

 down tlie two sides of the body, and in the hinder part was a large web of thin yellowish tissue. 

 Else the whole seemed structureless and of hyaline clearness. It contracted into a sliorter 

 oval figure." 



Harring (1917, p. 534, PI. 91, fig. 1—2) 



gives a figure of the male but no description. 



Description. Body cone-shaped, without any real lorica, extremely hyaline 

 tapering behind and provided with two well developed toes. A frontal hood, formed 

 as an extremely hyaline plate. Wheel-organ a ventrally placed quadrangular disc, 

 covered with a coating of short hairs, laterally limited by two patches, covered with 

 a similar hair coating; two conspicuous red eyes. The whole body cavity filled with 



