8 ENTOMOLOGICAL NEWS [Jan., '19 



head of the enclosed imago, which presses against the cephalic 

 extremity of the puparium, causing a rupture to take place 

 along lines, or pseudosutures, previously existent. As a mat- 

 ter of fact the similarity between the cap-like lid left on 

 the empty cocoon of species in Orthorrhapha and that of 

 the other suborder on the puparium, which is merely the 

 larval skin, is more imaginary than real, as the cap in the 

 latter consists of at least 2, and often 4, distinct pieces. The 

 cocoon of Orthorrhapha and the puparium of Cyclorrhapha 

 are not identical in character, the former having no physio- 

 logical relation to the insect, and to show evolutionary rela- 

 tionships it is essential that the same physiological features 

 be compared. 



In this paper I describe a new species of the genus Medeter- 

 tis. Unfortunately no larvae were preserved as the specimens 

 were merely side-products of another experiment. I have 

 already recorded the fact that the imagines of one species at 

 least of this genus in North America are predaceous. The 

 larvae have the same habit. 



Medeterus caemlescens sp. n. 



$ and $ . — Metallic blue ; frons, center of face, thorax and abdo- 

 men distinctly gray pruinescent. Antennae, palpi and proboscis black. 

 Face deep blue, becoming violet-colored below antennae. Dorsum of 

 thorax not distinctly vittate, the pruinescence most distinct in center 

 anteriorly; pleura brighter blue than dorsum, especially below. Abdo- 

 men with a blue-green tinge; processes of hypopygium yellowish. Legs 

 black, extreme apices of femora and bases of tibiae and basal half of 

 midmetatarsus yellow. Wings clear, veins black, paler at bases. Post- 

 ocular cilia white; bristle above fore coxa black; tegular cilia black. 

 Halteres yellow. 



$ . — Third antennal joint higher than long, with a slight indentation at 

 insertion of arista, the latter very long", almost bare ; face of equal 

 width on its entire length ; palpi with a few hairs. Dorsum of thorax 

 with 2 rows of acrostichals on anterior half; scutellum with 2 strong 

 apical and 2 weaker sub-basal bristles ; propleural bristle short. Hypo- 

 pygium long, reaching almost to base of venter, the processes slender. 

 Fore tibia without bristles ; mid tibia with the usual 2 bristles ; basal 

 joint of mid-tarsus nearly as long as joints 2 to 5 combined, the entire 

 tarsus slightly longer than tibia; hind tibia rather thick, with weak 

 hairs, which are most distinct on apical half of posterior surface, no 



