49 237 



especially in Ihe young animals. As well known, especially with regard lo [liiilnlinn, 

 Leydig has regarded the corns as nrine concrements, and the sac itsell' as a rudi- 

 ment of the alimentary canal. Weisse and Cohn regard them as j'olk masses, de- 

 ri-ving from egg. Weber follows the last named authors. Size of female 4 — 500 fi, 

 of male 200— 250 /i. Time: March— May. 



Rhinops vitrea Hudson. 



Male: Rousselet 1897 a, p. 6. 

 Tab. X, fig. 1—2. 



Rousselet (1897a, p. 6. PI. I) describes the male as follows: 



The shape of the male differs somewhat from that of the female; the body becomes 

 suddenly narrower in the lumbar region, whilst in the female it tapers very gradually down 

 to the toes. The body is very lithe and soft, bending constantly in ever\' direction. The corona 

 with its proboscis-like dorsal projection rosemtjles that of the female in every way, and two 

 red eyes are in the same manner situated near the extremity of the proboscis, each having 

 a minute spherical crystalHne lens imbedded in the red pigment. A dorsal antenna is seen on 

 the dorsal side, a little below the eyes, and the two lateral antennæare very conspicuous at the 

 projecting angle of the lumbar region each furnished with a brush of abnormally long setæ; 

 in the female the lateral antennae are very small. The foot is short, consisting apparently of 

 one joint containing the two foot-glands, and terminating in two minute toes. The chief cha- 

 racteristic and the most abnormal feature about this male is the possession of functional 

 jaws and intestine. The jaws are like those of the female in structure, but in one specimen 

 I thought the right malleus shorter than its companion on the left side. The oesophagus is 

 a thin, narrow tube leading to an elongated thick-walled stomach, with two gastric glands 

 attached, and continued behind into a narrow intestine, all ciliated in the interior. The jaws 

 were frequently moving, but the contents of stomach and intestine were very slight and of a 

 greenish tinge, without solid particles of large size. It seems clear, however, that the male 

 of Rhinops can take in some food, and therefore sustain life and live longer than all other 

 known male Rotifers. There is a rounded spermsac, at the lower end of which the sperma- 

 tozoa could be plainly seen in motion, terminating in a duct with the usual retractile and 

 ciliated copulatory organ. A small contractile vesicle and lateral canals with llame cells at- 

 tached are present as usual. Size of male 188—212/«. Size of female 300 fi. Time May. 



Description: Bodj' more elongated than in the female; it becomes suddenly 

 narrower in the lumbar region, whilst in the female it tapers very gradually down 

 to the toes; the foot very long. The body is very soft and extremely hyaline. As 

 in the female a long clubshaped proboscis proceeds dorsally; it can be more or less 

 distended and retracted. When living it is always distended, but when the animal 

 is dead, it may almost wholly disappear, and especially when the animal is seen 

 laterally, be very inconspicuous. In these animals also the foot is withdrawn, so 

 that it seems much smaller than it really is. (See Tab. X, fig. 2.) Wheel-organ highly 

 developed and very difficult to study. It consists of a ciliary wreath, provided with 

 two flattened, large auricles; dorsally it is almost interrupted, not coating the sides 

 of the proboscis; ventrally it shows a deep furrow. On the disc another ciliary 

 wreath, running from the sides of the proboscis in great curves downwards and 

 meeting the above-named furrow. Where these two ciliary wreaths meet each other, 



D. K. D, VidensU. Selsk. Skr., naturv. oj; muthem. Afd., S. RajkUe. IV. 'i. 32 



