20 
bands at the joints; the spiracles are inclosed by a black chitinous 
eminence, and there is a broad black band on the last segment, broken 
near the middle. (See Fig. 8.) 
a a 
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J 
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: 
: 
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Fic 8.—Hematopinus urius; a, female; b, male, ventral view of posterior segments; c, leg, showing | 
protractile disk of tibia. (Original.) + | 
| 
The male has the abdomen marked beneath with a large black area 
extending forward from the end of the terminal segment, soas to occupy 
the central portion of the last three segments. | 
There is a curious provision in the feet for strengthening the hold 
upon the hair, which does not seem to have been hitherto described. 
It consists of a circular pad-like organ or disk in the outer portion of 
the tibia which is received in a conical cavity in the end of the tibia, 
and which can be forced out so as to press upon the hair held between 
the claws ot the tarsus and the end of the tibia. 
Ordinarily, and always in the dead specimens, this is withdrawn so 
as to appear simply as a part of the end of the tibia, and the spines 
located on its margin, appear to belong to the tibial rim, but if exam- 
ined with sufficient magnification when the louse is alive it is easy to | 
observe the extrusion of the organ. | 
_ Whether similar organs exist in related species is yet undetermined, | 
but it seems quite probable that they should, since in the specimens 
examined microscopically we have usually to deal with dead and pre- | 
served individuals in which this structure would almost certainly escape 
notice. 
The eggs are one millimeter and a half in length (.06 in.) by three- 
fourths of a millimeter in width (.03 in.). They are light yellow or dusky 
