:ii!8 ZOOLOGY. 



nervous mass, we know well that it is the result of a fusion 

 of several ganglions. 



Anatomists liiul in the cephalic ganglions the analogues of 

 the brain, and in the knotted cord of insects the spinal mar- 

 row of the vertebrata ; but such views are questionable, and 

 if any analogy existed, it would rather be found in the gan- 

 glions situated on the posterior roots of the spinal nerves. 



510. In respect of the nervous and locomotor systems, 

 the annelides stand higher than the mollusca; but, as regards 

 the functions of vegetative life, their circulatory system is 

 less complete, and is occasionally altogether absent. In gene- 

 ral their blood is white, but not in all, and this difference 

 seems not much to affect them. Their mode of respiration 



mis k e j 



n I q q p o 



Fig. 337. Anatomy of the Butterfly Sphinx.* 



varies ; their digestive tube extends from one extremity of the 

 body to the other; the mouth is placed in the head, and 

 the anus at the other extremity. Finally, there exist almost 

 always jaws, or at least particular instruments for the pre- 

 hension ot'the food, and these organs are alwa3 r s disposed late- 

 rally, in pairs, instead of vertically, and before each other, as 

 in the vertebrata. 



This primary division is subdivided into two groups : first, 

 articulated animals, properly so called; second, vermes or 

 worms. In these there are no limbs, or at least they are 

 represented merely by tubercles furnished with hairs (sc-ti- 

 2rous), and the organs of generation are so degraded as to 

 >me at last extremely imperfect. 



* The different parts are indicated by the same letters as in the preceding 

 figure. 



