GfeAND DIVISIONS. 13 



larva to crysalis, from cry sal is to the perfect ia- 

 sect. They are generally the most voracious 

 while in the larva state. Some live long in the 

 larva state, and but a short time in the state of 

 the perfect insect. As the cicadia septendecim 

 (American locust,) remains in the larva state sev- 

 enteen years, and in the state of perfect insect 

 hut about a week, and eats nothing during that 

 period. Others are in the larva state but a short 

 time in proportion to their duration in the insect 

 state ; as niusca domestica, the common house-fly, 

 which continues a long time and eats continually* 



Animals of this division were probably created 

 before the vertebral. For it is said that the cast- 

 off crusts of the crysalis of some species are found 

 in older rocks than the bones of vertebral animals. 

 I have never found any such relics. Perhaps 

 flsh are found in formations about as old as any 

 0f this division. 



Examples. Angle worm, leach, lobster, spi- 

 der, beetle, cricket, bee, butterfly, gnat. 



IV. VERTEBRAL ANIMALS. 



In this division the sentient principle is lodged 

 in a medullary substance, the basis of which is in- 

 closed in a bony tube, composed of a column of ver- 

 tebrae. 



To the nervous axis enclosed in a bony tube; 

 which is called the medulla spinalis, there is an 

 appendage at one extremity, denominated the 

 train. This is inclosed in a bony case, called the 

 cranium. But animals of this division have au- 

 other system of nerves, more analagous to the sys- 

 tems found in the other three divisions; than the 



