BDELLOID ROTIFERA OF SOUTH AFRICA. 57 



tended. It is one-lialf wider than the collar and twice as wide as 

 the neck. The sulcus width is about three-fourths that of each 

 disc, and is fully occupied by the boldly outlined and charac- 

 teristic upper lip, consisting of two fine lobes and an intervening 

 part with a boldly notched anterior border. It is rather difficult 

 to get a good view of the corona, as the head is kept moving cease- 

 lessly when feeding. Even when creeping, it has a restless, 

 jerky, fussy manner. Though it does not get over the ground 

 very fast, it is very forceful, and brushes its way under and 

 through the rubbish with great vigour. 



The rostrum is stout and fairly long, and has a triple arrange- 

 ment of the lamella. There is a well-marked rosette round the 

 closed mouth. The antenna is a mere stump, about one-sixth 

 of the neck width. There are no eye-spots on the rather large 

 brain mass. 



The jaws are relatively small, and are crossed by four or five 

 teeth of no great size. There is great difficulty in making quite 

 sure of the number of teeth, on account of the restless habits of 

 the animal and the density of the integument and parts overlying 

 the dental bulb. There is a large gland below the mastax, darker 

 in colour and finely granulated. The lumen is narrow and has 

 a yellow investment. The intestine is large, and the contractile 

 vesicle small and of short period. 



The rump is well marked off from the trunk and is heavy. 

 The foot is cleanly modelled, very short and equal to about one- 

 twelfth of the total length. The second and third segments are 

 each very short. The foot glands are very heavy and extend well 

 up through the anal segment. The spurs are very distinctive and 

 handsome ; the great globular bases are quite unique, and the 

 short cones seem set into them. 



The foot and trunk are delicately and closely stippled. 



The only Bdelloid nearly related to this is Mniobia tetraodon. 

 In some points there is a considerable resemblance between the 

 two. The samples of M. tetraodon which I have seen agree with 

 those found by Bryce in the upper lip and size, but are more in 

 accord with Janson's account (3) in the spread of the corona. I 

 find cases of corona to collar as 15 : 14. In some the proportion 

 was slightly greater, but none showed so great a proportion 

 as Bryce mentions. The upper lip in mine agrees with Bryce' a 

 description (4). The upper lips in the two species are not very 



