34 PROCEEDINGS OF THE NATIONAL MUSEUM VOL. 92 
the specimens a smooth, glossy coat. Both claspers are then stuck 
with glue or thick balsam on a clean slide, one showing internal view 
and the other external, and may be studied as opaque objects by direct 
lighting with an ordinary dissecting binocular. The detail to be seen 
by this method is considerably more than is possible with cleared 
mounts. The mounts can be made permanent if protected from dust 
by a cover glass supported on bits of cork or cork rings. 
Genus STREPTOCEPHALUS Baird 
STREPTOCEPHALUS DOROTHAE, new species 
Ficures 4, B; 5, B 
Description.i—The clasping antennae present definite characters 
that may be noted at a glance. The appendage is rather slender, and 
the first two segments are much wrinkled on the surface. The spinous 
processes in a row on the internal surface of the second segment are 
long and numerous, but this is not a reliable character. The third 
segment, or scissors, affords the best identification marks. The 
internal shorter branch bears two processes at the base on the anterior 
surface (fig. 4, B, at f). The shorter proximal one of these curves 
sharply inward (in fig. 4, B, toward the observer). The distal process 
is long and slender and curves around the body of the appendage and 
thus is partly hidden from internal view. (Compare these processes 
with the homologous structures in S. texanus shown in fig. 4, A, at ce.) 
Toward the distal end of the inner branch of the scissors, shown at d 
in fig. 4, B, is a swollen area, the anterior surface of which is thin- 
walled and apt to be wrinkled. There is no process on the posterior 
side as in S. texanus. (Compare with fig. 4, A, at @ of S. texanus.) 
One character of the external longer branch of the scissors is distinc- 
tive: The peculiar shape of the end of the posterior spur, which projects 
from near the base proximal to the “‘elbow”’ (fig. 4, B, ate). I have 
likened this shape of the end of the spur to a tiny foot, seen from side 
view, the rounded bump on the lower side being the ‘‘heel’’ and the 
point the ‘‘toe.”” (Compare the spur with that of S. teranus, fig. 4, A, 
at 6, which is in the form of a smooth-pointed blade.) After comparing 
hundreds of specimens of S. dorothae and texanus, I am convinced 
that these characters of the claspers are constant. One character of 
the swimming appendages may be of value: In S. dorothae the bract 
is serrate over the entire outer margin. In S. teranus there are only 
a few small spines on this margin at the proximal end, and the re- 
mainder is smooth. 
1 In this diagnosis I have eliminated characters of generic and family rank. For instance, if there is nothing 
distinctive about the first antennae in peculiarities of shape, segmentation, etc., I see no necessity for noting 
the presence of the appendage, since it is present in all the Streptocephalidae. Thus I have omitted dis- 
cussion of many characters usually mentioned in descriptions of streptocephalids, hoping to focus attention 
on those of most value. I do not find streptocephalids difficult to identify, and I am convinced that diffi- 
culties experienced by others are due to confusion of species by Packard and other earlier writers. 
