160 



GROSSE S CLASSIFICATION AND 



Nitsch divides them into two chief groups — PniLOPTERiDiE 

 and LiOTHEiDiE. The Philopteridae have filamentous antennae 

 and no palps : the Liotheidse have clavate four-jointed antennae 

 and palps. The Philopteridae comprise two families : (i) Tricho- 

 DECTES, the only genus, characterized by three-jointed antennae 

 and one-clawed feet; (2) Philopteridae, strictly with five-jointed 

 antennae and two-clawed feet. 



The LiOTHEiD^ have likewise two families : (i) Gyropus, the 

 only genus having one-clawed feet ; and (2) Liotheid^, stricte^ 

 with two-clawed feet. 



Trichodectes and Gyropus occur only on mammals, the 

 other genera only on birds, and are classified according to the 

 presence or absence of appendages on the head (trabeculae) and 

 their motility, to the sexual differentiation of antennae, their atti- 

 tude, the form of the head, the consistency of the thoracal 

 somites, and the form of the last abdominal somites. 



Philopterid^, strict}. 



1. Trabeculae motile, antennae nearly alike in 



both sexes ... ... ... Docophortis. 



2. Trabecule not motile. 



a. Antennae filiform, no sexual differentiation. 



(«) Hind-head rounded off, terminal 



somite of male rounded off ... Nmnus. 



{b) Hind-head abruptly angled, abdo- 

 minal somites fused in the middle Goniocotes. 



b. Antennas of male forcipate by a process 



from the third segment. 



{a) Hind-head angled, terminal somite 

 of female tubercle-like, of male 

 rounded off ... ... Goniodes. 



(b) Hind-head rounded off, terminal 



somite of male notched ... Lipeurus. 



Liotheid/E, strict}. 

 I. Mesothorax wanting, antennae generally concealed. 



a. Head very broad, no orbital sinus ... Eureunu 



b. Head elongated, with lateral aijgles 



directed backwards. 



