BDELLOID ROTIFERA OF SOUTH AFRICA. 63 



The rostrum is stout and has four or five setae on each side, 

 two of the longest have bulbous roots and are quiveringly vibra- 

 tile. The lamella is trifid (fig. 3/), but only so seen when the 

 rostrum tip is fully exserted, and pressed firmly against the cover- 

 glass preparatory to pulling it away. Murray (10) states there 

 are two separate lamellae, but the appearance of two is due to 

 the middle part being hidden when the tip is only just showing. 

 Before the grip of the glass is taken, the lamella is clearly seen 

 with a fold in the middle, and not two separate parts. When the 

 rostrum is tossed back, it has a peculiar appearance — two roundish 

 parts in an almost rectangular casing. 



There is a curious ribbon of thin skin, of considerable width, 

 extending forward from the posterior of the rostral segment, and 

 right round, at least dorsally and laterally. It stands clear of 

 the segment at its front. Murray's figure seems to show it. 



The antenna is stout and long, and equal to one-half of the 

 neck width. There are three knobs across the top, and three 

 brushes of short setae protrude ; muscle or nerve threads pass up 

 the middle. It is independently motile and it frequently gives 

 a decided bend, the top segment also does so by itself. It is 

 evidently very sensitive ; for preparatory to exserting the head 

 when the body is contracted, the antenna is gently protruded, 

 and if it should meet an obstacle is drawn back, but again a 

 second or even a third time it may be quietly pushed up to the 

 obstacle, as if to ascertain its nature. The animal has evidently 

 two very sensitive feelers : the antenna, and the cilia with the 

 bulbous roots in the rostrum. 



There are no eye-spots on the medium-sized brain mass. 



The jaws are extremely large — l/520th inch — and somewhat 

 heart-shaped ; and the borders are thickened with rough brush- 

 like extensions (PL 3, fig. 36) often stained bright yellow. The 

 four large teeth are pointed, and of a peculiar shape — swollen 

 towards the inner ends and tapering off outwards. The fifth 

 tooth is quite half the size of the largest, and the striae are very 

 large. The double fulcrum (PL 3, fig. 3e) can be seen, during 

 feeding, when the jaws are horizontal and open. 



The vascular canals are prominent in the neck and are sur- 

 rounded by a large amount of floccose matter, and there are at 

 least five vibratile tags on each side. There may possibly be more, 

 as the internal structure is not easily discernible on account of 



