4 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



The following points in which the Lithobiidae differ from the Heni- 

 copidae may be mentioned as the most important thus far noted : 



1. The labrum is tridentate instead of unidentate. 



2. The inner branch of the first maxillae is armed with ramose or 

 plumose hairs. 



3. The outer branch of the first maxillae is only biarticulate. 



4. When present, the eyes consist of from several to many ocelli. 



5. Sternite of prehensorial segment absent, never constituting a 

 distinct transverse sclerite or collar. 



6. On none of the legs is a true tibial process or spur ever present. 



7. Articular spines are present on at least part of the legs cephalad 

 of the fourteenth pair. 



8. Anal pores never present in adults. 



9. Gonopods of male composed of one or, at most, of two articles 

 and never terminating in a pointed process or rudimentary claw. 



In regard to point 7 it may be mentioned that in Watobius and 

 allies (subfamily Watobiinae mihi), which differ from the typical 

 Lithobiidae in other points also, spines are present only on the tibiae 

 in the place occupied by the tibial spur in the Henicopidae; while in 

 the Henicopidae spines may very rarely occur on trochanter or on tro- 

 chanter and prefemur of the fourteenth and fifteenth pairs of legs. 



The following definition of the Henicopidae is based primarily 

 upon a study of the North American representatives. 



HENICOPIDAE (char, emend.'). 



Labrum mesally deeply incised; unidentate; margins of lateral 

 divisions bearing either plumose or else simple or nearly simple 

 hairs. 



Inner branch of first maxillae armed with simple hairs exclusively, 

 or in part with hairs simply and shortly laciniate at tips. Outer 

 branch triarticulate; clothed distally with plumose hairs. 



Palpus of second maxillae triarticulate; claw four or five partite; 

 distal article bearing on ventral surface toward distal end few to many 

 plumose (ramose) hairs. 



Eyes either entirely absent or consisting of a single large ocellus on 

 each side\ 



Organ of Tomosvary large; situated on ventral border of head, 

 typically caudad of position of ocellus. 



Sternite of prehensorial segment well developed, extending trans- 



