506 K. I. MARKS AND W. WESCHE 



the males of Brachionus with which he was acquainted, and also 

 in the males of some species of Floscularia, Lacinularia, and 

 Stephanoceros. He also saw it in females, and did not consider it 

 an exclusively male character. In B. loala he saw traces of a 

 vesicle containing the black mass, which observation we are 

 enabled to endorse by our experience of B. quadratus^ wherein 

 the mass of granules was enclosed in a distinct membrane. Dr. 

 Leydig considered the granules to be urinary concretions 

 (" Harnconcremete ") analogous to the chalky fluid which is 

 discharged by many insects after their evolution from pupae. 

 In B. quadratus the granules are in constant agitation, reminding 

 one of the cyclosis seen at the ends of some Desmids — Closterium, 

 for example. 



The spermatozoa have a different movement. Intermixed 

 with them in the sperm-sac were a number of circular masses 

 of protoplasm, with a few granules at the sides. The spermato- 

 zoa difler from those figured in this Journal, November, 

 1902, PI. 17. They are angular in shape, and have no bulb 

 at either extremity; but one end is thick, swelling to a blunt 

 23oint, situated at about one-third from the end. The other 

 end is acutely pointed. Some were seen outside the body, and 

 from these measurements were obtained and drawings made. 

 The length of these spermatozoa was x/oQ^h inch (=15, a) 

 (Fig. l,c). 



The males of the Brachionidae are very similar in appearance, 

 hut some have marked characters that make them easy of 

 identification ; B.2)cda, for instance, has a distinctly triangular eye, 

 and the dorsal antenna is situated at some distance behind the 

 head. In addition, the body contains numerous oil globules 

 which are usually absent in other species. 



Several females of B. quadratus were seen with resting eggs 

 (Tig. 1, d). Mr. Rousselet informs us that these are very 

 uncommon, and as their production is generally thought to depend 

 on fecundation by the male — i.e. they are not parthenogenetic 

 •eggs — their extreme rarity is easily explained. 



The granular mass alluded to was not present in the other 

 male rotifers we describe. In some water from a pond at 

 Neasden were many females of the small loricated free 

 swimmers — Anuraea hrevisjnna Gosse ; A. aculeata with fairly 

 long spines, yet not so long as we have sometimes seen them ; 



