38 



The nrotlioi.i.'ic iln<f is iincbanged, while the nietathoracic ring is already 

 much dimiuislied in size, and the oiillines of the primitive form of the meso- 

 scntum are indicated. 



Fig. 2 represents an extremely interesting stage ; the prothoracic ring 

 is now much smaller ; the mesothorax is large ; the scutum is well marked ; 

 while the mctathorax indicates the scutum deeply hollowed out, apparently 

 to receive the mesoscutellum. 



Figs. 3, 3o, 4, 4«, 5, 5«, represent a more advanced stage. The thorax 

 is more swollen, and has assumed somewhat of the characteristic form of the 

 imago, but the abdomen is still as seen in the larva. 



In figs. 6, 6a, the semi-pupal condition is nearly completed. The pro- 

 portions of the three thoracic segments now approach those of the imago. 

 The prothorax is still undiflerentiated ; but the scutum is well marl?ed, though 

 the drawings do not indicate that the scutellum has been separated from the 

 scutum. The abdomen is now much contracted, and of the pupal proportions. 



Fig. 7 is a dorsal view of the end of the semi-pupal stage. 



Fig. 8 represents the pupa. Owing to the paralyzed, enfeebled state of 

 the hirva, the ends of the wings have not reached the end of the depression 

 in the under side of the abdomen. 



The facts here given are, however, sutiicient to show that the transtbr- 

 niation of the larva into the pupa is a very gradual process, and may be com- 

 pared with the stages that I have already showed to exist in the semi-pupal 

 condition of Bomhus* It seems that (he pieces of the thorax are indicated 

 during (his slage, but lliat the scutum of the prothorax and mctathorax do not 

 s(!panit(.' until tiie close of the pupal lite, while the mesoscutellum does not 

 become diiferentiated luitil after pupation. This process must go on in the 

 hypodermis ol' llu; i)U])a, which is dcslincd to form tlie imaginal integument. 



§11. — Skcondary sexual chakactkrs of the imago. 



The inore apparent sexual chaiaclcis of the adult Phahenids consist in 

 the antcnnce being ciliated or pectinated in the male, and simple or sub- 

 simple in the It-male. The head in trout is wider in the female than in the 

 male, as in other Lcpidoplcni. The wings, jtarticnlarly the anterior pair, are 

 broaihu- and blunter at the apex in (he males tiian in the females. The abdo- 



" Observations ou tbo Duvelopuient and Position ol' tlie Hyuienontera. — Proceedings Best. Soc. Nat. 

 Hist., X, 1866, 279. 



