24 TETTIGID.E OF NORTH AMERICA 



was usually drawn out or stretched at first, but appeared to 

 diminish in length a little as the parts were undergoing the 

 adjustment and change to their natural proportions. The hind 

 femur was weak and the tibia was pliable for a short period 

 immediately following its redrawal from the empty cuticle. 

 The cast-off cuticle was left still grasping the ground, the 

 head part thrown down and the rent along the dorsum gaping.* 

 The newly metamorphosed insect finally crawled up a stalk of 

 grass to get the full benefit of the sun and take on the normal 

 pigmentation. 



PHYLOGENV AS SUGGESTED BY THE METAMORPHOSIS. 



In the temperate region all the species have a climacteric 

 period, one in which the insects on becoming mature enter a 

 new phase of existence different from the preceding last pupa 

 stage. This final period of metamorphic perfection (imago) is 

 characterized by the establishment of the sexual functions 

 and taking on of distinctly adult characters. The elytra 

 shift their position to the sides of the body and the wings 

 become explicate and functionally perfect. With some of the 

 tropical species, on the other hand (see Choripkjlliiin, Plate I.), 

 this distinctly metamorphic stage, denoting a period of anabolic 

 surplus of vitality, is not so apparent, there being no external 

 evidence of a distinct period between the last pupa stage and 

 imago. The insects here referred to are wingless and have no 

 elytra or any anatomical place provided for them, the sinus 

 for their reception at the usual point at the side of the body 

 being absent. The seasons alone can not be responsible for 

 this peculiar con lition, for we also find species in the tropics 

 living near-by possessing elytra and wings. It seems to be 

 in a large measure due to the reaction of the organism to the 

 environment, effecting in turn an adaptation of structure to a 

 special purpose, obviously of a protective character. In 

 this evolution these Tettigids have suffered the loss of the 

 marked distinction of pupa and imago characteristic of other 

 Tettigidse, whose metamorphosis is apparently one stage 



*A maW Paratettix cucuUaius \n the author's collection had never completely discarded 

 the cuticle during life. It is attached to the distorted pronotum. 



