OF WASHINGTON. 213 



Here there are only two transverse carinae, the areas being want 

 ing. 



In figs. 3, 4, 5, and 6 I show some of the characteristic 

 forms of the metathorax observed in the family Chalcidida3. In 

 fig. 3 the metathorax is produced into a subglobose neck at 

 apex, while there are three longitudinal carinae, the two lateral 

 usually being designated as the lateral folds. 



In fig. 4 the median carina is wanting, while in fig. 5 is ex 

 hibited a form entirely without carina. In both of these figures 

 the metathorax is not produced into a subglobose neck. 



In fig. 6 I show a character not apparent in any of the others. 

 This is a grooved line or channel extending from the spiracle to 

 the apical margin, which is termed the spiracular sulcus. It is a 

 valuable character in the classification of the Chalcididae. 



In figs. 7, 8, 9, and 10 I show some typical forms of the meta 

 thorax observed in the subfamily Microgasterince in the family 

 Braconidce, which I find to be of great importance in dividing 

 this group into sections. In fig. 7 we have a median area or 

 areola, in fig. 8 a median longitudinal carina, in fig. 9 it is per 

 fectly plane without either areola or carina, while in fig. 10 the 

 apical margin is deeply bisinuated. 



While on the subject of the metathorax, I desire to call special 

 attention to another character of primary importance, entirely, 

 or almost entirely, neglected by systematic workers ; that is, the 

 shape and position of the metathoracic spiracles. These should 

 always be defined, at least in our generic descriptions. 



On the plate I have figured some of the more important 

 forms: Fig. 1 1 is round or circular; fig. 12 oval; fig. 13 ovate; 

 fig. 14 elliptical; fig. 15 reniform or kidney-shaped; fig. 16 

 linear; fig. 17 curved linear. 



The wings and their venation have always been considered of 

 the first importance in classification, and their value is not over 

 estimated. In fact, our system of classification in all orders 

 to-day, except in the Coleoptera, is based mainly upon venation. 



To enter fully into the subject of venation, as found in the 

 Parasitica, would occupy much time, and I shall only be able 

 to-night to draw attention to a few special types and point out 

 to you the value of some characteristic features of these in 

 systematic work. 



