442 NEW YORK STATE MUSEUM 
Part a 
SIALIDIDAE OF NORTH AND SOUTH AMERIGA 
BY SG. Cie DAVIS 
The study leading to the preparation of this paper was made chiefly while 
the writer was a graduate student at Cornell University, 1898-1900. The 
. writer is under great obligation to Prof. J. H. Comstock and Mr A. D. Mac- 
Gillivray; of Cornell, for much aid and encouragement; to Mr Samuel Hen- 
shaw, of the Museum of Comparative Zoology, for-use of the rich collec- 
tions made by Dr Hagen and others; to Mr William H. Ashmead for the 
examination and loan of valuable specimens from the United States. 
National Museum; to Dr Henry Skinner for kindness shown while examin- — 
ing specimens in the Philadelphia Academy of Natural Sciences; and to a 
number of correspondents and others who have given information in re- . 
gard to distribution, or lent specimens for examination, or aided in other 
ways. 
The family Sialididae is of peculiar interest both on 
account of the large size and the striking appearance of most 
of its members and because it includes some of the most general- 
ized members of the order Neuroptera. 
As is often the case with more primitive groups, the family 
is a small one, including only four living genera; but it has a 
world-wide distribution. Fortunately for our purposes, all of 
the genera are found in our country, and representatives are 
common in many sections. The four genera are represented in 
the two Americas by only 32 species. 
Family SIALIDIDAE | 
The members of this family differ from all other Neuroptera 
in having the hind wings broad at the base, the anal area being 
folded like a fan when the insect is at rest. They differ from 
their nearest allies, the Raphididae, in the form of the pro- 
‘thorax, which is quadrangular, while in the Raphididae it is 
generally elongated. They also differ from most other Neurop- 
tera in being aquatic in their larval state. 
Though the.family contains only four living genera, these ~ 
represent two quite distinct lines of development. So well 
marked are these that they may be considered as representing 
two subfamilies, which may be designatéd as the Sialidinae and 
