CHAMBERLIN: HENICOPIDAE OF AMERICA NORTH OF MEXICO. 5 



versely as a narrow sclerite or "collar" caudad of the prosternum 

 proper. 



Tibia of all legs, or of all excepting the last one to three pairs, bear- 

 ing at the distal end on the cephalic or cephalodorsal side an acute 

 or spinous tipped process or spur. True articular spines either wholly 

 absent (as in all N. Amer. species) or present only on last two pairs 

 of legs. 



Spiracles present on 3rd, 5th, 8th, 10th, 12th, and 14th segments, 

 as in the Lithobiidae, or, in addition also on the 1st; or rarely present 

 only on the 3rd and 10th segments (Catanopsobius). 



Coxal pores present on the last two to five pairs of coxae. 



Anal pores always present in adults and consisting of a single well- 

 developed pair opening into a common median passage. 



Gonopods of female long, triarticulate, and ending in a stout, 

 strongly chitinized claw which is always entire; basal spines, so far 

 as known, 2 + 2 or 2+3. 2nd article glabrous dorsally. Gonopods 

 of male likewise long and triarticulate; ending in a straight, weakly 

 chitinized process usually terminating in a bristle. 



Three genera of this family are at present known to occur in America 

 north of Mexico. They may be separated by means of the following 

 key. 



aa. A pair of spiracles on the first leg-bearing segment. 



Henicopinae Chamb. 



Tarsi of anterior legs undivided. Lamyctes Meinert. 



aa. No spiracles present on the first leg-bearing segment. 



Zygethobiinae Chamb. 



b. Ocelli absent; only the coxae of the last four pairs of legs bear- 

 ing pores. Buethobius Chamberlin. 

 bb. A pair of large ocelli present; coxae of last five pairs of legs 

 bearing pores. Zygethobius Chamberlin. 



LAMYCTES Meinert. 

 Naturh. tidsskr., 1868, 5, p. 266. 



Labrum of usual form; lateral pieces not notched each side of 

 median tooth; sides bearing sparse and simple hairs. (Plate 1, fig. 6). 



Inner branch of first maxillae bearing few and entirely simple hairs. 

 Outer branch armed with simple and plumose hairs. (Plate 1, figs. 3 

 and 4). 



