280 ANATOMY. 



very evident anteriorly, but nearly obliterated posteriorly. In the 

 larvae of the Dytici I likewise found a short nervous cord with closely 

 contiguous ganglia, whence the auxiliary nerves proceed, and yet their 

 bodies exhibit twelve distinct segments without the head. Perhaps 

 this imperfect development of their nervous system is in relation to 

 their constantly dwelling in water ; at least the same structure in the 

 equally distinctly jointed larva of Stratlomys, which likewise con- 

 stantly lives in the water, points to one and the same cause of an 

 analogous imperfection. 



The positive opposition to this abortion of the nervous cord is found 

 in the caterpillars of the Lepidoptera and the larvae of many beetles. 

 All these exhibit a ventral cord, which has as many ganglia as the 

 body has segments, and in which, like the segments of the body, all the 

 ganglia are of equal size. We must, however, here remark that a 

 ganglion is not found in each segment, but that they gradually approxi- 

 mate together, so that the last ganglion, which follows immediately 

 upon the preceding one without any connecting cord, is found as far 

 advanced as the anterior margin of the penultimate segment. Each 

 ganglion sends off four nervous filaments, the first pair of which 

 extend more anteriorly, and the posterior pair furnish the parts 

 lying behind the ganglion with their nerves. But the nerves of the 

 ventral cord are almost exclusively destined to the organs of motion, 

 and they consequently distribute themselves with their branches be- 

 tween the upper and lower layers of the muscles. In some cases the 

 most internal muscles, particularly those lying about the cavity of the 

 abdomen, receive a peculiar nervous branch, and which is found in the 

 larva of Cossus ligniperda, and which here does not originate from the 

 ganglion itself, but closely in front of it, from the there simple undi- 

 vided connecting cord ; it commences with a small root, which speedily 

 divides into two equal branches, which take an opposite direction *. 

 In the larva of Calosoma sycophant a I found six nervous filaments 

 proceed from each ganglion, the middle pair of which likewise re- 

 mained above the ventral muscles, whereas the anterior and posterior 

 pairs passed beneath. The nerves for the anterior portion of the 

 intestinal canal come from the cerebrum, and form a peculiar system, 

 which descends that canal ; the nerves of the sexual organs proceed 

 indeed from the ventral cord, but merely from the branches of the 



* Lj-onct. ri. ix. 1. 1. :, -i, -2. 



