744 Journal of Agricultural Research vol. xx.No. w 



epipharynx, tentorium (arms and bridge), hypopharynx, maxillae, 

 labium, and mandibles. 



The epicranium is the largest area of the head, extending from the dor- 

 sal margins of thefrons and the lateral margins of the adfrons on the an- 

 terior wall of the head to the dorsal margin of the occipital foramen and 

 the lateral margins of the hypostomaon the posterior wall. The epicranium 

 is divided dorsally by a rather faint, median line, the epicranial suture 

 (PI. 90, G) , from the dorsal angle of the f rons to the occipital foramen, 

 and has a pair of slight, parallel seams beginning near the lateral extrem- 

 ities of the occipital foramen and extending a short distance dorsally. 

 It is moderately spined generally but has concentrations of spines in 

 the areas about the antennas, eyes, and pleurostomata. The eyes (Pi. 

 90, A, D) are a single simple pair, one occurring near each of the lateral 

 extremities of the head and slightly below a line drawn through the 

 dorsad -later ad angles of the frons. The antennae (Pi. 90, F) are paired 

 and occur one each about midway between each eye and the nearest 

 portion of the pleurostoma. They consist of an elongate projecting cone 

 anteriorly and two flat, floating pieces beyond, one of which is usually 

 faintly connected with a narrow band running forward around the cone. 

 Thefrons (Pi. 90, G) is an inverted, somewhat shield-shaped area and has 

 for its dorsal margin an angle projecting into the epicranium with its 

 apex at about the height of the head's greatest width. Its lateral mar- 

 gins are nearly parallel and about equal in length to the distance of 

 their separation, while the ventral margin is moderately concave. This 

 sclerite is spined according to a rather regular pattern, but the number 

 of spines and their position vary somewhat. The adfrons (Pi. 90, G) 

 consists of an elongate area of thick chitin situated laterad of the frons 

 and separating it from the epicranium. In outline each adfrons is some- 

 what triangular and supports the dorsal attachment of a tentorial arm 

 and the dorsal or anterior condyle for the mandible. The pleurostomata 

 (Pi. 90, B) are the thickened lateral margins of the epicranium which 

 extend in an arc around the base of each mandible and support 

 at their anterior and posterior extremities the points of articulation 

 of each mandible. The hypostoma (PI. 90, B) is a centrally narrowing 

 bridge with its dorsal margin formed by the somewhat angular lower 

 rim of the occipital foramen, its ventral margin formed by the 

 slightly curved posterior rim of the buccal foramen, and its lateral limits 

 defined by the slightly curved and thickened ridges running from the 

 lateral extremities of the occipital foramen to the ventral or posterior 

 fossae for the mandibles. The clypeus (Pi. 90, B) is a dorsally chitinous, 

 ventrally membranous area immediately below the frons and connect- 

 ing it with the labrum. It is armed with two pairs of spines arranged 

 to form a transverse row. These pairs are separated from each 

 other about two and a half times the distance between the individuals 

 constituting the pair. The labrum (Pi. 90, I) is slightly bilobed 



