180 THE CANADIAN ENTOMOLOGIST. 



Amongst those already known may be mentioned Agriotypus armatus, 

 Walker, which is confined (as are the others) to the European fauna, and 

 has been observed swimming beneath the water, being parasitic on the 

 larvae of various Trichoptera. It forms a family of its own, probably 

 related most closely to the Ichneumonidae. Polynema natans belongs 

 to the Mymarinse (Proctotrypidae), and resembles in method of swimming 

 Marchal's species, but its wings are somewhat abortive, and it is thought 

 that it cannot fly well. It is parasitic on the eggs of Calopteryx. Lastly, 

 Prestivichia aquatica, said to be a Chalcid, is parasitic on the eggs of 

 Notonectus and Dytiscus, as observed by Lubbock and Enoch, and swims 

 with its legs instead of its wings. 



Marchal places his genus within the Proctotrypidae, subfamily 

 Scelioninae, close to the genus Thoron. For its characters I must 

 refer the reader to the original memoir. 



So far as I know, aquatic Hymenoptera are as yet unknown to the 

 American fauna. But there should be — at least, it is quite likely that there 

 may be — some species which has adopted an aquatic life here as well as in 

 Europe. Who will be the first to find one ? 



TWO NEW SILPHID.E FROM COLORADO. 



BY H. F. WICKHAM, IOWA CITY, IOWA. 



Silp ha Colorade?isis, n. sp. — Form of incequalis, but more elongate, 

 black, except the tip of the abdomen, which is orange-rufous; above 

 clothed with short black hairs. Head densely punctate, the punctures 

 regular over the greater part of the surface, those in front of the 

 inter-antennal line smaller and less distinct ; occipital transverse 

 impression deep; labrum short, broadly emarginate ; antennae black, 

 club four-jointed, the last three joints pubescent, the terminal one longer, 

 compressed, tip sinuately rounded. Thorax about one and one-half times 

 as broad as long, narrowed anteriorly, sides broadly arcuate in front, 

 more suddenly so behind, basal lobe slightly and very broadly emarginate. 

 Surface somewhat irregular, densely and very regularly punctate, sides 

 somewhat flattened. Scutellum slightly concave, densely punctured. 

 Elytra as wide as the thorax and fully twice as long, the sides nearly 

 parallel, outer margins distinctly reflexed, apices conjointly rounded, but 

 sinuate externally, punctuation less dense than that of the thorax, each 

 puncture with a recumbent hair. Disk flat, more suddenly declivous at 

 sides than in incequalis, each elytron with three costa>, the outer of which 

 is much the best marked, being high, acute, not terminating opposite the 



