480 



ROTIFERA I TARDIGRADA. 



iv. The fourth of M. Dujardin's primary orders consists of the 

 very curious tribe, first carefully investigated by M. Doyere, to 

 which the name of Tardigrada has been given, on account of the 

 slowness of their creeping movement. Their relation to the true 

 Rotifera, however, is not at all clear ; and many naturalists regard 



Fig. 247. 



Noteus quadricornis ; A, dorsal view ; b, side view. 



them as altogether distinct. They are found in the same localities 

 with the Rotifers, and, like them, can be revivified after desicca- 

 tion (§ 362) ; but they have a vermiform body, divided trans- 

 versely into five segments, of which one constitutes the head, 

 whilst each of the others bears a pair of little fleshy protuberances, 

 furnished with four curved hooks, and much resembling the pro- 

 legs of a caterpillar. The head is entirely unpossessed of ciliated 

 lobes ; and it is only in the presence of a pair of jaws somewhat 

 resembling those of Rotifera, and in the correspondence of their 

 general grade of organization, that they bear any structural rela- 

 tion to the class we have now been considering. They may be 

 pretty certainly regarded as a connecting link between the Rotifera 

 and the Worms ; but they should probably be ranked on the worm- 

 side of the boundary. 



364. Notwithstanding that all the best-informed Zoologists are 

 now agreed in ranking the class of Rotifera in the Articulated 

 series, yet there is still a considerable discordance of opinion as to 

 the precise part of that series in which they should stand. For 



