58 



INTRODUCTION TO ZOOLOGY. 



double " ganglions," as these nervous masses are termed, 

 from which are given off the nerves that proceed to the 

 extremities. From the symmetrical disposition of these 

 nervous centres, Mr. Owen has given to this sub-kingdom the 

 name Homogangliata.* The body in general presents a cor- 

 responding symmetrical form, and consists of a repetition of 

 rings or segments, as in the Earth-worm, or the Millepede 

 (Julus, Fig. 37). 



Fig. 37. JULUS, 



The articulated animals are arranged in the following 

 classes : 



Annellatct) Leeches, Earth-worms, &c. 

 Cimpeda, Barnacles and Acorn-shells. 

 Crustacea., Crabs, Lobsters, &c. 

 Insecta, Beetles, Bees, Butterflies, &c. 

 Arachmda, Spiders, Scorpions, and Mites. 



'* From two Greek words, one signifying " similar,'' the other " a 

 ganglion," or knot, being the mass of nervous matter from which the 

 nerves diverge. 



