352 THE GROUSE IN HEALTH AND IN DISEASE 



describing them as lobes without any traces of palps. They are rounded and 

 First ^^^^' certain sette on them. When in motion they are shot up and pulled 



maxillae. down between the mandibles and the labium or fused second maxillae ; 

 sometimes both are moved forward at once, sometimes they move alternately. 



V. The Second Pair of Maxilla . — These have fused together and form a labium 

 of a very simple kind. There is a median plate or mentum in which we found no 

 Second transversc furrow. This plate bears anteriorly a pair of one-jointed pro- 

 inaxiiipe. ccsses ending in a few short stiff bristles. These are called by Grosse the 

 paraglossse, but, as there are a pair of minute one-jointed processes internal to these, 

 it may be that they represent the palps. AVhichever they are, they are very mobile, 

 and are constantly being divaricated into a position at right angles to the normal, 

 and then suddenly brought back again. They are obviously of use in bringing 

 food to the mouth. The more median processes as well as the palps bear hairs. 



A median structure which we think may represent the hypopharynx is the 

 lyriform organ, or the " oesophageal sclerite" of Kellogg. This median piece is 

 strongly chitinised, deep brown in colour, and consequently conspicuous; it seems 

 to lie about in the same level with the first maxillae, except when they are protruded, 

 when it lies behind them. A muscle on each side of the oesophagus runs from the 

 anterior angle of the sclerite to the dorsal side of the head, and brings al)out the 

 movement of the organ. Kellogg has described in certain species a pair of oval 

 glands which lie ventral to the sclerite, and the ducts of which unite and open by a 

 common duct into the median groove of the thickening. These glands are very 

 conspicuous in Goniocles, and are shown in several of our figures. Their function 

 is unknown. Their ducts are cross-barred like a trachea. The whole sclerite is 

 conspicuous and shines through as a somewhat V- or U-shaped dark area, visible 

 from above. As Kellogg points out, a similar apparatus exists in the Psocidse. 

 Two salivary glands on each side of the oesophagus have been described in many 

 genera of Mallophaga. The ducts of all four unite and open into the pharynx by 

 a common duct. 



The second maxillse are so minute and feeble that we found it impossible to 

 dissect them out even from macerated specimens. 



VI. The Prothoracic Legs. — These pair of appendages are turned forward and 

 Prothoracic their ends normally lie underneath the mouth. They doubtless take some 

 '^^^' part in bringing food to the mouth. Their inner ends are approximated, 



so that the sternum here is but little more than a line. Snodgrass ' records that 



' "Occasional Papers of the California Academy of Sciences," vi. p. 152, 1899. 



