279 [Packard. 



February 7, 1866. 

 The President in the chair. 



Thirty-eight members present. 

 The following paper was presented : 

 Observations on the Development and Position of the 



HYaiENOPTERA, WITH NOTES ON THE MORPHOLOGY OF InSECTS. 



By a. S. Packard, Jr., M. D. 



The following notes form an abstract of a more extended memoir 

 upon the changes of the insect after leaving the egg, not touchino- 

 upon the evolution of the embryo. 



After the larva has become full fed, as it is about to enter upon tlie 

 semi-pupa state, its body undergoes the following changes : The tho- 

 racic rings and head become more elongated and fuller, so that 

 where in the larva the under side of the anterior and posterior halves 

 of the body are closely appressed to each other, now, the two halves 

 begin to recede, and the grub as it lies in its cell, is but half doubled 

 upon itself With this important change of posture the whole body 

 becomes more cylindrical and rounded. Thus the sides {Artliropleurod) 

 of the thoracic ring become absorbed, and do not project out from the 

 walls of the body as in the larva; and later still, the coiTCspondino- 

 area in the abdomen likewise almost wholly disappears. 



The greatest activity, however, is observable about the cephalic 

 portion of the body, for here the greatest differentiation of parts 

 is to occur. The head of the pupa, already partially formed beneath 

 the prothoracic ring, though as yet very small, by its presence still 

 affects very sensibly the form of this region in the larva, the skin of 

 which still remains unbroken, though very considerably distended. 

 The whole length of the head (Fig. 1, a,) and prothorax (Fig. 1, h,) 

 together, is now equal to the united length of the head and thorax in 

 the larva originally. To effect this, the larval head is greatly 

 extended forwards, and the prothorax is three times as lono- as before, 

 and much narrower, the sides converging towards the base of the 

 head. The two posterior thoracic rings are also twice as long as in 

 the larva. On the under (sternal) side the mouth parts are also 

 elongated, and the labium projects a little beyond the head, owing to 

 the increased size of the mouth-parts over those of the larva. 



At this period, the two pairs of wings are very equal in size, the 

 posterior pair but little smaller than the anterior pair, and inserted 



