150 CALIFORNIA ACADEMY OF SCIENCES. 



edges. They lack palpi and distinct divisions into the 

 ordinary parts (plate x, figs. 8 and 10). 



The labium presents two forms, one in the Amblycera 

 the other in the Ischnocera. In the former (plate x, 

 fig. 9), there are present a submentum, mentum with 

 two four- segmented palpi, and a ligula with two glossse 

 and two paraglossa3. The ligula is the only part that 

 varies much, since it may have more or fewer than the 

 four lobes named. In the Ischnocera a submentum, 

 mentum, and ligula are present. The latter two are not 

 well separated, but the paraglossae are distinct (plate x, 

 fig. 13) and very constant in form, being short, thick, 

 cylindrical, and rather more chitinized than the rest of 

 the labium. The glossse are present between the para- 

 glossse as two small lobes. 



In front of the mouth is the labrum, a large lobe sit- 

 uated on the ventral aspect of the head, generally some 

 distance back of the anterior border of the clypeus. 



The three pairs of legs are 

 very similar throughout the 

 group. The tarsi are two- 

 jointed, and, with the excep- 

 tion of two genera, Tricho- 

 decte.s and Gyropus, that in- 

 habit mammals, are provided 

 with two claws, the others 

 having only one. In some 

 specimens of Dbcoplwriis ciii'- 

 soT examined, the legs when 

 at rest generally assumed 

 the following positions. The 

 femur (fig. 1) of the metatho- 

 racic leg extends outward and ^.^ ^ 



is inclined slightly forward 



