140 GRAMMAR OF ENTOMOLOGY. 



then again divide, and, passing one on each side of 

 the gullet, reunite below it, and enclose it in a ring. 



524. At the union they form the third cerebroid 

 {mesothoracis cerebroida) ; and from this arise four 

 principal nerves, two of which (mesopedum nervi) de- 

 scend to the feet, and two others (prothoracis nervi 

 dorsales) ascend to the back ; the cord then again 

 separates, to re-unite in the mesothorax, where 

 it again gives rise to four nerves. 



525. After forming the fourth, fifth, and sixth 

 cerebroids, separating in the same way between 

 each, the cord proceeds single, and united to the 

 propodeon, and through the other segments to the 

 telum, leaving a distinct mass or cerebroid in each 

 segment, which invariably gives out four nerves, 

 two of which ascend to the back, and the other 

 two descend, some entering the prehensile legs, 

 with which most caterpillars are furnished. 



526. In the telum is situated the thirteenth and 

 last cerebroid {teli cerebroida), and this gives off 

 no less than eight nerves, most of them permeating 

 the organs of generation : thus the number of 

 main nerves arising from the whole of the cerebroids 

 in this caterpillar, is sixty-two. 



527. The twelfth and thirteenth cerebroids are 

 attached and sessile without any intervening 

 cord ; the spaces between the others vary very 

 rapidly as the insect approaches perfection. 



528. In the first place, the second cerebroid 

 enters the head, and becomes united with the first ; 



