A. ie See ey 
ret eS 
år 
1886.) Grosse’s Classification and Structure of the Bird-lice. 343 
on the under side of the head. In all Liotheidæ it is similarly 
formed (Fig. 1 ZÆ), being a thin transverse arched swelling, with 
chitinous margins bearing small bristles. The labrum of the 
Philopteridæ has a broad disk-like basis fixed on the under side 
of the head, and is divided by some transverse furrows (Figs. 2, 
3,5%). There is a broad furrow, separated from the mouth by a 
| The large pointed teeth 
‘cles held between the lab- 
(Fis inner side of the blade has hooklets (not in Decophors) 
Mee 5,6). The maxilla seem to take no part in comminu- — 
plate of chitin, and farther forward a deep narrow furrow, next 
the anterior boundary of the labrum. In the living animal the 
labrum is constantly moving; and in Philopteridz it can adhere 
to glass like a suctorial disk. The labrum can thus hold on to 
hairs or feathers. 
Mandibles—As a type we take the mandibles of ge 
mus (Fig. 4). They have 
each two strong, lon 
teeth, somewhat different 
in their structure 
The under tooth of the 
left mandible has a pro- 
tuberance with curved 
point and an arched sur- 
face; its upper tooth has 
two points, The right 
mandible has two stout 
teeth which fit the leftos M .@ 
mandible on closing. This 
Serves for cutting parti- 
rum and the first maxilla. 
serve for removing dermal 
scales, The mandibles ofthat 
Fic. kan and left adii of Tetroph- 
xX Fic. 5.—Head pes hd ig 
the Philopteridze are long, £708 ‘eae een from below. X 60. Fic. 6— 
Wo- $ 
trian gular and First iie of Tetrophthalmus, X 75. 
wan the teeth short and thick (especially in genus Doco- 
ang maxille—These are conical, and have a basal and a ter- 7 S 
minal segment or blade, distinguishable in young spe ee 
the food beyond aiding in its prehension. With al care 
