11 8 Book-lice and Bark-lice ; Biting Bird-lice 
beculoe, triangular membranous processes projecting laterally from the head and situated 
one in front of each antenna; temples, the hinder lateral parts of the head; ocular emar- 
gination, a bending in of the lateral margins of the head just in front of the eyes; labral 
lobes, short blunt membranous processes projecting laterally from near the front angles 
of the head; sternal markings, blackish markings, bars or spots, on the ventral aspect of 
the thorax. 
Key to Suborders of Mallophaga. 
With short slender 3- or 5-segmented, exposed antennae; no palpi; mandibles 
vertical. Ischnocera. 
With short clavate or capitate, 4-segmented antennae concealed in shallow cavities 
on under side of head; 4-segmented palpi; mandibles horizontal. 
Amblycera. 
Key to Genera of the Suborder Ischnocera. 
A. With 3-segmented antennae; tarsi with one claw; infesting mammals only (family 
Trichodectidce) .Trichodectes. 
AA. With 5-segmented antennae; tarsi with two claws; infesting birds only (family 
Philopteridce ). 
B. Antennae alike in both sexes. 
C. Front deeply angularly notched. Akidoproctus. 
CC. Front convex, truncate, and rarely with a curving emargination, but never 
angularly notched. 
D. Body broad and short; head with large movable trabeculae. 
E. Forehead with a broad, transverse membranous flap, project¬ 
ing beyond lateral margins of the head in the male, barely 
projecting in the female— . Giebelia. 
EE. Without such membranous flap. Docophorus. 
DD. Body elongate, narrow; head with very small or no trabeculae. 
Nirmus. 
BB. Antennae differing in the two sexes. 
C. Body wide, elongate oval to suborbicular. 
D. Temples rounded; tip of abdomen with shallow, curving emargina¬ 
tion; antennae with no appendage; third segment unusually long. 
Eurymetopus. 
DD. Temples usually angulated; tip of abdomen convex, rarely angularly 
emarginated with two points. 
E. First antennal segment of male large, and sometimes with 
an appendage; third segment always with appendage. 
Goniodes. 
EE. First antennal segment of male large, but always without 
appendage; third segment without appendage. .Goniocotes. 
CC. Body elongate, narrow, sides subparallel. 
D. Antennae and legs long; a semicircular depression in front of 
mouth. Lipeurus. 
DD. Antennae and legs short; depression in front of mouth narrow and 
elongate, extending as a furrow to the anterior margin of the head. 
Oncophorus. 
Key to Genera of the Suborder Amblycera. 
A. Tarsi with one claw; infesting mammals only (family Gyropidce ). Gyropus. 
AA. Tarsi with two claws; infesting birds only (family Liotheidce). 
B. Ocular emargination distinct, more or less deep. 
