404 ZOOLOGY. 



glionary portion is composed in them of only one or two 

 pairs of ganglions situated on the median line of the body ; 

 whilst in the annelides we find a long series of ventral gan- 

 glions ; and when we find in this part of the body merely a 

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

 fusion of several ganglions. 



Anatomists find 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 locomotive 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 

 varies ; their digestive tube extends from one extremity of the 



n I q q p o 



Fig. 415. Anatomy of the Butterfly Sphinx.* 



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 of the food, and these organs are always 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, verities or 

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

 represented merely by tubercles furnished with hairs (seti- 

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

 become at last extremely imperfect. 



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

 figure. 



