June, 1907.] American Species of Papirius. 161 
However, MacGillvray in The Canadian Entomologist, Vol. 
XXV, gives some further characters which are of value in separat¬ 
ing Smynthums from Papirius. His characterization is as 
follows: 
A. Terminal segment of antennae long, ringed; larger claw uninden- 
tate; apical segment of spring simple. Smynthurus. 
B. Terminal segment of antennae short; with whorls of hairs; larger 
claw bidentate; apical segment of spring serrate on the under side. 
Papirius. 
Of the general characters of the family, Papirius possesses 
most of them. The antennae are long and slender, and often 
distinctly annulated; however these annulations have been the 
source of not a little confusion of the genus with Smynthurus; 
many investigators failing to see the division between the third 
and fourth segment. Still by careful examination there may 
always be found a distinct line separating the two joints. 
The legs are generally long, the larger claw bearing two c r 
more teeth. The spring is very long, and well adapted for leap¬ 
ing; the dentes and mucrones in most cases being serrated. 
The ventral sucker is highly developed, and on agitating the 
insect it may be seen to throw out the long tactile filaments 
from the sucker. 
The segments of the globular abdomen are fused; only the 
terminal segment being distinct. Dorsal tubercles are present 
in some species and also tenant hairs. The eyes are distinctly 
black, with prominent ocelli. The head in all species is loosely 
joined to the body. 
The one characteristic of Papirius which distinguishes it from 
Smynthurus and Dicyrtoma is the four-jointed antennae, with 
the short terminal segment. Smynthurus has a four-jointed an¬ 
tennae, but the fourth segment is long, while Dicyrtoma has an 
eight jointed antennae. This character of the short terminal 
segment in Papirius is marked enough to make it quite a distinct 
genus. 
General Anatomy. 
The general plan of structure of this genus does not differ 
materially from, that of other insects, and with the exception of 
the terminal joint of the antennae does not differ at all from the 
type of the family. 
The Body, as in all Smynthuridae , is globular in shape, and 
the abdomen consists of six segments, the average length of the 
entire animal being about 1 mm. The shape of the body may 
vary to oval as in novoeboracensis , or sub-triangular as in te'xensis, 
while unicolor has a slightly reentering angle at the terminal 
segment. 
The Head, is about as long as broad, and joined loosely to 
the body. On its upper surface are the black eyespots. These 
