Genus ERETMOCERUS Haldeman. 
Eretmocerus Hald., Amer. Journ. Science, vol. 1x, pp. 110, 111, May, 1850. 
This genus, which Haldeman did not place, was put by Cresson, in 
his Synopsis, in the Mymarinz, which subfamily was located with the 
Proctotrypide. The reason for this placing was probably the fact that 
Haldeman placed the genus Amitus, described immediately before Hret- 
mocerus, in the Mymarine. Mr. Ashmead, in his monograph of the 
Proctotrypide, places Amitus in the proctotrypid subfamily Platygas- 
terinze, and in making the necessary studies upon this genus, recognized 
the aphelinine affinities of Hretmocerus, the antenne figured by Halde- 
man resembling very considerably the antenne of the gut. Plasto- 
charis Foerster. In studying a series of parasites reared by Mr. 
Coquillett in California from Aleyrodes, I have been delighted to recog- 
Fic. 1.—Hretmocerus californicus Howard: female, showing side view of genitalia below— greatly 
enlarged (original). 
nize a form which belongs, with little doubt, to Hretmocerus. Halde- 
man described the genus only from two mutilated specimens reared 
from Aleyrodes corni, and which he states were “imperfectly examined.” 
Among Mr. Coquillett’s specimens were fortunately many males, so 
that I am able to redescribe the genus in full. The differences between 
the form which I have studied and Haldeman’s description are as 
follows: 
Haldeman states that the tarsi are “apparently pentamerous,” eyes 
hairy, and antennal club oar-shaped (whence the generic name). 
In the form which I have studied, the tarsi are 4-jointed (a diserep- 
ancy owing, no doubt, to the fact that I have been able to see them 
clearly under a high power), the eyes are not hairy, and the antennal 
