BDELLOID ROTIFERA OF SOUTH AFRICA. 53 



horizontal direction. Without losing its hold, it may even bend 

 its body quite round on itself, and search with the rostrum along 

 the moss and rubbish to which the toes are attached, scraping off 

 particles as already described. It can search in this way, without 

 once shifting its hold, a circle of which its body is the radius — a 

 provision of great service to it, as it lessens the chances of its 

 being swept away by the swift current in which it lives. 



There are the usual telescopic joints on the foot and neck, 

 and though these slip out and in at times, I do not remember 

 ever having seen one contracted into a ball. Dead specimens 

 are always fully extended, with two toes showing the sickle shape, 

 and two contracted into their sheaths. 



The jaws at a first glance seem to be of the nature of some of 

 the Ploima, but are quite different. They are in two parts (right 

 and left) exactly alike, without any connecting single fulcrum. 

 The mallei are of the simplest, consisting of two rods jointed 

 together, both mallei being in the same plane. In the normal 

 jaws nearest in general appearance, e.g. Albertia, the central 

 rami and fulcrum are united together and form one part. In 

 M. falcatus, however, the fulcrum has been, as it were, cut in two. 

 There are thus two exactly similar portions (right and left) quite 

 separate from each other, and 

 accordingly different from any y 



arrangement obtaining among ^ 



the Ploima. Each fulcrum has 

 become an exceedingly short and 

 minute rod, visible only under 

 very favourable circumstances. 

 It is transposed to the anterior 

 and lies between the uncus and 

 ramus ends, articulated or mus- 

 cularly attached to each. There 

 is evidently a glassy plate con- 

 necting ae and ce^, for in some of the larger examples several 

 fine striae were seen between, thus indicating a link with the 

 Philodina jaws. 



The jaws seem to have two actions : a blinking, pecking action, 

 somewhat like that of some of the Notommata ; and a slightly 

 rotating one, a little approaching that of Philodina, but jerky 

 jiistead of the even, steady motion of the latter. 



