STRUCTURE OF THE MALLOPHAGA. 163 



normal first maxillae, and bears the four-jointed labial palps. The 

 upper part is the ligula or glossa (g.), corresponding to the inner 

 blade (lacinia). Laterally on the ligula are the paraglossse (/.), 

 corresponding to the outer blade (galea). A chitinous band 

 limits the glossa where it bears the paraglossa, as if the parts of 

 both had coalesced. 



Rudow seems to have mistaken the antennae for the labial 

 palps. Melnikow overlooked the labium, and erroneously com- 

 pared the products of the oesophageal intima with the proboscis of 

 Pediculina, in consequence of this false comparison referring the 

 Mallophaga to Rhynchota. 



The labium of the Philopterid^ has no palps (Figs. 7). It 

 is usually triangular, with rounded angles, and is sometimes very 

 small, as in the genus Lipeurus, the mentum being smaller than 

 the ligule. The ligule is emarginated in Docophoriis and Lipeurus. 

 The paraglossae of Philopterid^, as in the Liotheid^e, are Hke 

 tactile organs, remarkably long in species of Goniodes. 



In all LiOTHEiDiE the intima of the ventral end of the oral 

 cavity forms a fold-like duplicature as in Philopterid/e (hypopha- 

 rynx. Fig. 2, hy.). In LcBmobothriuin and Tetrophthalmus this 

 extends forward over the labium, and its lateral borders are 

 strongly bent upwards (Figs, i, 8, hy.). 



For the study of the head Grosse made transverse and saggital 

 sections of specimens fresh from moulting and hardened in chromic 

 or picric acid. From absolute alcohol they were placed in chloro- 

 form, and after two hours embedded in paraffin, being kept for a 

 time in melted paraffin under the air-pump. The sections were 

 attached to the slide by means of albumen or oil of cloves, 

 stained by alcoholic carmine-solution, treated with acidulated 

 alcohol so as to show the nuclei, and then enclosed in Canada 

 balsam. 



Thorax. — In the genera Trinotum, Colpocephalum^ and Tetroph- 

 thalmus^ the three thoracic somites are present, especially manifest 

 in the young. The prothorax of Tetrophthalmus has above a 

 rounded swelling, and ends forwards in a bristly point on each 

 side. Within the prothorax, but visible through the transparent 

 dorsum, is a cross-band of chitin, as in Meuopon^ for the attach- 

 ment of muscles. The mesothorax is much narrower than the 



