PBIMABY DIVISIONS AND CLASSES. 217 



namely, mammals, birds, reptiles, batrackia, and 



Fig. 175. The Leech. 



380. In the primary division of the entomozoaria, or 

 annulated animals, we observe modifications of structure no 



Fig. 176. Nereis ; called b the Dover fishermen " the Mud-worm." 



less remarkable. Sometimes, as in the talitrus, there exist 

 articulated limbs serving as levers in the apparatus of loco- 



Fig. 177. Kotifera ; Wheel-bearing animals. 



motion ; and the cephalic portion of the ganglionary nervous 

 system acquires considerable importance. Sometimes, on the 



-**^^ 



Fig. 178. Ascaris ; an intestinal worm. 



* In the early editions of this work, the vertebrata were divided into four 

 classes, following Cuvier's arrangement ; the batrachia for good reasons have 

 since been separated from the reptilia. 



