346 



MALLOPHAGA 



under side of the head. The eyes are very rudimentary, and 

 consist of only a small number of isolated facets placed behind 



the antennae ; sometimes 

 they are completely absent. 

 The mouth parts are situ^ 

 ated entirely on the under- 

 surface of the head and in 

 a cavity. The upper lip 

 is frequently of remarkable 

 form, as if it were a scrap- 

 ing instrument (pi, Fig. 



FIG. 215. Under-surface of head of Lipeurus 215). The mandibles are 

 heterographus. (After Grosse.) ol, Labium ; sharply toothed and appar- 

 md, mandible ; mx, maxilla ; ul, labium. . . 



ently act as cutting instru- 

 ments. The maxillae have been described in the principal 

 work on the family 1 as possessing in some cases well-developed 

 palpi. According to Grosse 2 this is erroneous ; the maxillae, he 

 says, are always destitute of palpi, and are of peculiar form, being 

 each merely a lobe of somewhat conical shape, furnished on one 

 aspect with hooks or setae. The under lip is peculiar, and 

 apparently of very different form in the two chief groups of 

 Mallophaga. The 

 large mentum bears, 

 in Liotheides (Fig. 

 216, B), on each side 

 a four-jointed palpus, 

 the pair of palps 

 being very widely ^TT ^iC^ 

 separated; the ligula 

 is broad and undi- 

 vided ; on each side 



bearing an oval pro- 

 cess, and above this 



is a projection of the hypopharynx. In Philopterides (Fig. 216, 

 A) the palpi are absent, and the parts of the lower lip are 

 with the exception of the paraglossae but little differentiated. 

 The lingua (hypo-pharynx) in Mallophaga is largely developed, 



1 Giebel and Nitzsch, Insecta epizoica, folio, 1874. 

 2 Zeitschr. wiss. Zool. xlii. 1885, p. 537. 



-py 



pi 



FIG. 216. Under lip of JTzVwn/s, A; and of Tetroph- 

 thalmus chilensis, B. (After Grosse.) m, Mentum ; 

 g, ligula ; pi, palp ; pg, paraglossa ; hy, lingua. 



