24 MONOGRAPHIA 



GENUS III. HxEMATOPINUS. 



Leach, Samouelle, Stephens, Burmeister. Pediculus, Linnaeus, De Geer, 

 Fabricius, Redi, Albin, Latreille, Nitzsch, Lamarck. 



GENERIC CHARACTER. 



HEAD variable in form, either globose, elliptical or lyrate ; 

 the anterior part truncate, rotundate or acute ; occiput 

 either truncate, rotundate or acuminate; either closely 

 inserted into the thorax, and equal in width, or con- 

 siderably produced, exerted, and much narrower. 



HAUSTELLUM in structure like Pediculus, but always more 

 produced, and protected on each side with stiff unciform 

 bristles. 



ANTENNJE of five joints, the first much enlarged, the 

 second generally the longest, the third and fourth cylin- 

 drical or transverse and nearly equal, the fifth generally 

 the smallest, conical, and terminated by a fasciculus of 

 bristles. 



EYES generally small and flat, sometimes inconspicuous 

 or probably absent, especially in the species infesting the 

 Rodentia. 



THORAX distinctly separated from the abdomen, and much 

 narrower ; the segments intimately united, generally 

 transverse, shorter and broader than the head; the anterior 

 part concave or notched, with a single spiracle between 

 the first and second pair of legs. 



ABDOMEN large, depressed, oval, ovate, or elliptical, of eight 

 or nine segments ; the sutures distinctly defined, the late- 

 ral margin reflexed, dentate or entire, surface papillose 

 or smooth, and shining. 



