446 CALIFORNIA ACADEMY OF SCIENCES. 



margin of the gula. Its posterior angles are much 

 rounded. Anteriorly it presents a concave border of 

 which the lateral portions are free, but the median part 

 bears the mentum. The submentum, on account of its 

 anterior and posterior concavities, is much constricted in 

 the middle. 



The mentum is a comparatively narrow, tranversely 

 elongated, unchitinized sclerite, attached posteriorly to 

 the submentum, but having its lateral borders free. The 

 anterior outer angles are rounded. The median portion 

 of the anterior border bears the glossal and paraglossae. 

 These are not separated by any suture from the men- 

 tum, and hence there is no distinct ligular sclerite. The 

 glossae are two small oval lobes situated on each side of 

 the median line and close to each other, being only 

 slightly separated. Each bears four or five large, strong 

 hairs situated on small basal segments. External to each 

 glossa is a rather deep fossa in the mentum. In these 

 fossae are situated the paraglossae. These are cylin- 

 drical structures having the outer ends somewhat en- 

 larged, and bearing six or seven large, strong, two-jointed 

 hairs like those on the glossa?. The paraglossae are rather 

 strongly chitinized compared with the rest of the labium; 

 they appear dark while the other parts are white. Each 

 is directed outward, forward, and downward. With the 

 exception of the hairs on the glossae and paraglossae 

 there are almost none on the labium. Two small ones 

 situated on basal joints occur on the mentum, one just 

 back of each glossa. The oddly shaped, cylindrical 

 paraglossae, having the stiff, thick, two-jointed hairs on 

 the flattened outer ends, are very characteristic of the 

 suborder Ischnocera. In undetached labiums there often 

 appears to be a narrow sclerite between the sclerites 

 which have been called mentum and submentum, but in 

 the mounted specimen this does not appear. 



