J. C. HUTSON 205 



the sternum of the mesothorax, and the coxae. The hairs on 

 the "dorsum" of the propodeum, the thoracic pleura, the pro- 

 thoracic lobes, the dorsal surface of the petiole and the undersides 

 of the trochanters and femora are perhaps not quite so dense and 

 coarse as those in the first class, but the gradations are so slight 

 that no marked line of distinction can be drawn. The smallest 

 erect hairs occur on the dorsal portion of the sixth or terminal 

 segment of the female abdomen and along the sides of the ventral 

 portions of the abdominal segments in males and females. 



Certain areas of the integument are marked by more or less 

 parallel grooves known as "striations," other parts by fine 

 irregular raised lines enclosing shallow punctured areas and giving 

 a condition known as "rugose." 



These insects do not show any startling color markings or 

 bands, the body being more or less evenly colored with shades 

 of metallic blue, black, or green, sometimes with purple or violet 

 reflections. As mentioned above, the actual body color is some- 

 times obscured by the closely-set vestiture of fine pubescence. 



The wings may be dark brown to pale fuliginous, even in the 

 same species, or they may be hyaline with fuscous tips, and in 

 most cases may show violet to bluish reflections in certain lights. 



External Anatomy 

 Head 



The head is medium to large, broader than high, and seen from 

 above is transversely elongate. The compound eyes are large, 

 somewhat oval structures, extending from the sides of the vertex 

 almost to the base of the mandibles. Seen from in front they 

 occupy together an area about equal to that which lies between 

 them, while on a side view each eye covers about twice the area 

 of the cheek which lies behind it. They are narrowest at the 

 top, where they are bluntly rounded, and gradually expand 

 towards the bottom, where they are broadly truncate with a 

 slight emargination to receive the lateral extensions of the clypeus. 

 The eyes may be nearer each other at the vertex than at the clyp- 

 eus, as in females, or the reverse, as is the case in males of the 

 species dealt with in this paper. 



Clypeus. — The clypeus is roughly a trapeziform plate lying 

 below the antennae and occupying the lower central portion of 

 the front of the head, with its lower angles extending laterally 



TRANS. AM. ENT. SOC, XLV. 



