1928] 
A Note on the Genus Pelecinus 
207 
almost entirely by thelytokous females and the tropical forms 
by a comparatively equal proportion of males and females. 
The systematic position of Pelecinus has always been a 
matter of disagreement among hymenopterists. Ordinarily it 
has been regarded as a highly modified member of the super- 
family Serphoidea (Proctotrypoidea), but recently Handlirsch 
has considered it to form a superfamily annectant between the 
Terebrantia and Aculeata. Considering its highly specialized 
form and isolated position it is impossible to determine the rela- 
tionships of Pelecinus with any great degree of satisfaction. 
Some recent studies which I have made upon the fauna of the 
Baltic amber lead me to believe that the recent Pelecinus has 
been derived from a type represented by the very primitive Ste- 
phanidse through types existent in the early Tertiary that I am 
inclined to believe show a derivation of Pelecinus from a Ste- 
phanid-like ancestor. 
Such being the case we have in Pelecinus a primitive type 
which has become modified in certain regions to a thelytokous 
method of reproduction, such as is seen in certain very much less 
primitive parasitic Hymenoptera of the superfamily Ichneumo- 
noidea. In most of these, arrhenotoky prevails although a few 
cases of thelytoky have been observed and frequently normal 
arrhenotoky with the occasional production of a very few females 
in the brood. Evidently the appearance of thelytoky in Pele- 
cinus is definitely related to climate and may be regarded as a 
recent acquisition. 
In 1894 5 Patton described a second North American species 
from Tennessee to which he gave the name of P. brunneipes. 
This he distinguishes from P. polyturator by its smaller size, 
lighter legs, the presence of an oblong brown cloud in the first 
cubital cell behind the stigmal cloud, the presence of puncto- 
reticulate sculpture on the disc of the propodeum in place of the 
transversely arcuately rugose sculpture of P. polyturator. I have 
had in my collection for a number of years a very small female 
Pelecinus taken by Prof. W. M. Wheeler at Colebrook, Conn., in 
August 1910, which is probably the form described by Patton. 
It differs very markedly from all of the numerous females of P. 
‘(Amer. Naturalist, vol. 28, p. 896). 
