OF WASHINGTON. 307 



In the Ichneumons the two joints of the trochanters are distinct, 

 and nearly equal in size in many species. 



9. The long, straight filiform structure of the antennae of Rho- 

 palosoma is unquestionably a strong character against its belong 

 ing to the Vespidae. 



10. The front of the thorax of Rhopalosoma is similarly 

 formed to that of Ophion. 



11. The ocelli of Rhopalosoma agree with thdse of Ophion. 



12. I know of no Ichneumonideous, nor indeed any other 

 Hymenopterous insect, with feet like those of the female Rhopa 

 losoma, whereas they are simple in the male. 



13. The pedunculated basal segment of the abdomen of Rho 

 palosoma occurs in many groups of Aculeata. as well as in many 

 of the Terebrantia. 



14. The sting of Rhopalosoma is a genuine aculeus, with a 

 broad sheath. 



15. The lobed base of the hind wing, and the 6-jointed max 

 illary palpi, which latter character occurs in no genuine Ichneu 

 mon, must not be overlooked in determining the relations of the 

 genus. 



After this very complete summary, for and against this insect 

 being an Ichneumonid, Prof. Westwood ends up with the fol 

 lowing remarks : 



"From the preceding discussion it will doubtless be considered 

 that whilst in several important respects the insect before us 

 agrees with some of the Ichneumonidae., it is in others, equally 

 important, allied to the Aculeata, forming by itself a most ex 

 ceptional and isolated section." 



The above summary will afford you an admirable idea of how 

 Doctors sometimes disagree, since the four mentioned Haliday, 

 Smith, Westwood, and Cresson are among the highest authorities 

 in the Hymenoptera. 



What has been given above seems to be all that has been writ 

 ten upon this remarkable genus up to the present time, except 

 that in my paper u On the Hymenoptera of Colorado," published 

 in Bull. No. i of Col. Biol. Assoc., 1880, without specimens of 

 my own for study. I made it the type of a new subfamily, the 

 Rhopalosominae, in the family Braconidae. 



Since that time, however, I have made a careful and thorough 

 study of the insect and now believe it to be no Braconid, but 

 agree with Haliday and Westwood and believe it to be a true 

 Aculeate. I go even farther and believe it to be the type of a 

 distinct family of fossorial wasps, with affinities allying it to the 

 Vespidae, Sapygidag, and Scoliidae, and propose for it the family 

 name Rhopalosomidce. 



It is, according to my views, a connecting link between the 



