ON A NEW SPECIES OF CANTHOCAMPTUS FROM 
IDAHO. 
BY C. DWIGHT MARSH, 
Professor of Biology, Ripon College. 
Canthocamptus idaiioensis sp. new. 
This Canthocamptus was found in some material collected by 
Professor B. W. Evermann in Alturas Inlet, Idaho. 
There were only a few mature specimens of the form so that 
the description which follows is somewhat imperfect, but is suf¬ 
ficiently complete, perhaps, to characterize the species, which 
seems undoubtedly new. 
Length of the male .7 mm. The abdominal segments are 
nearly as broad as those of the thorax, and both abdominal and 
thoracic segments are serrated on their posterior borders, and 
armed with fine setae. Two dentations, one on each, side, are 
especially prominent on the abdominal segments. 
The branches of the furca (Plate IX, fig. 4) are slender, the 
length being about four times the average width, and the api¬ 
cal extremity about half as wide as the base. At about half 
the distance from the base to the apex there is a somewhat sud¬ 
den constriction in width, and at this point there is a group of 
rather small setae. The apex is armed with a long central seta, 
a short and weak external lateral seta, and a still shorter inter¬ 
nal lateral seta. 
The first antennae of the female (Plate IX, fig. 5) are eight 
jointed, and of the form typical for Canthocamptus. The first 
four segments are much larger than those which succeed, and 
are of approximately equal length. The relative lengths of the 
segments, commencing with the first, are as follows: 25, 23, 
21, 24, 7, 15, 8, 20. The first three segments have circlets of 
