670 
ANNUAL REPORT OF NEW YORK 
GARDEN FLEA. THE FORKED TAIL AND SKIPPING APPARATUS. 
the three pairs of legs being inserted upon the fore part of its under side. 
As it is viewed from above the body has a 
somewhat square outline, but is broadest pos¬ 
teriorly. The four sides of the square are, 
convex, with rounded angles, the rotundity 
increasing as it is more distended with food, 
and becoming globular when surfeited. It is 
plump and smooth, without any visible indica¬ 
tions of transverse impressed lines or sutures 
dividing it into rings; but, jutting abruptly 
out from the middle of its hind side is a large 
teat-like protuberance forming the end of the 
body, and this is- perceptibly composed of three 
segments, as is represented in the annexed figure. On its under side, how¬ 
ever, the body is uneven and transversely wrinkled, here showing four seg¬ 
ments more or less distinctly. And on its under side is also noticed the 
curious apparatus, the forked tail, wherewith these Garden Fleas possess 
the faculty of skipping. Two soft flesh-like threads are plainly percepti¬ 
ble, of a dull white color, and slightly diverging from each other, held 
against the breast with their ends reaching forward nearly or quite to the 
mouth. They seem to arise from the center of the under side of the body, 
but in reality are inserted into the end of a single stalk which it is more 
difficult to distinguish and which originates farther back toward the hind 
end. Thus this tail-like appendage is similar in its structure to a common 
table fork, of which the handle corresponds with the stalk or basal portion, 
and the tines with the two threads. These threads gradually taper towards 
their ends and are bearded with minute hairs, their tip being formed of a 
small oblong joint which is destitute of hairiness. On the fore part of the 
breast, bulging out between the two threads may be observed a slight pro¬ 
tuberance or button-like elevation, looking much as though the insect had 
a tumor upon its neck analogous to the disease termed goitre by physicians. 
And it appears to be in a groove upon each side of this protuberance that 
the inner sides of the threads are pressed when the insect is about to make 
a skip. Then, in an effort to extend the tail out from the body, the threads 
slipping suddenly from the grooves strike against the surface on which the 
insect is standing, so forcibly as to throw it a distance of several inches. 
The head is separated from the body by a deep constriction, leaving only 
a small neck connecting these two parts. It is about a third narrower than 
the broadest part of the body, more broad than long and of a flattened 
globular form The antennae are inserted upon the front, wide apart from 
each other at their origin, and are held obliquely forward and outward, 
each moment touching the surface over which the flea is walking, as if^ 
they were examining the nature of the pathway before it. These organs, 
represented greatly magnified on the right of the above cut, are thread¬ 
like, four-jointed, and elbowed in their middle between the second and third 
joints. The three first joints are cylindrical and of equal length. The 
fourth joint is longer and compound, being formed of six small joints, 
