Chamberlin — Neio Spiroboloid Diplopods. 167 



hind; head, antennae and legs brown. Sulcus of head widely interrupted 

 in the frontal region. Clypeal foveolae 4-f4. Upper clypeal region a 

 shallow depression on each side. Antennae reaching to second segment. 

 Collum moderately concave or excavated in front for reception of cardo 

 of mandibles. Lower end rounded. Second segment extending well below 

 level of collum on each side, the part below collum with lower and anterior 

 margins straight. Surface of segments punctate, with fine, short, mostly 

 longitudinal lines proceeding from the punctae. Covered part of pro- 

 zonites with few but distinct transverse striae. Sutures distinct through- 

 out, bending a little forward toward pores, which are small. Anal valves 

 moderately protruding caudad but not at all margined; exceeding the 

 anal scutum. The free inner edge of basal or coxal plate of anterior 

 gonopods a little shorter than the length of the median plate, with a short 

 blunt process at distomesal angle; the telopoclite distally narrowly rounded, 

 not at all bent or uncate. Posterior telopodites concave on posterior 

 surface distally — distal end rounded, the edges finely dentate, the mesal 

 edge with a prominent angle at proximal end of concave region; no free 

 median or inner piece. Number of segments fifty-three. 



Length (male), near 80 mm.; width, 8 mm. 



Locality.— California: Claremont. (W. A. Hilton.) 



ATOPETHOLIDAE, fam. nov. 



In this family the anterior median plate of the gonopods of male is 

 reflexed from distal end up on the caudal side, the caudal extension 

 commonly continued above in more membranous form and coming into 

 more or less intimate relationship with the bases of the posterior gonopods. 

 Posterior gonopods with telopoclite simple and mostly blade-like with 

 no separate inner piece; basal region often more or less extended mesad 

 at an angle suggestive of condition in the Trigoniulidae. In most forms, 

 at least, the telopodite of anterior gonopods distinctly articulated; short 

 and broad, with a finger-like or distally expanded process from distal or 

 mesal edge. The members of this family are easily recognizable among 

 other North American Spiroboloids by the form of the collum which is 

 acutely narrowed on each side below; caudal margin nearly straight above 

 these lateral processes, not much bowed caudad as in Spirobolus, etc.; 

 while the second segment is not at all produced below the level of the col- 

 lum. The family includes, in addition to Atopetholus and Hesperolus, 

 the two new genera described below, also Onychelus, Eurelus, and related 

 genera of the southwestern United States and Mexico. 



Atopetholus, gen. nov. 



In this genus the anterior median plate of the male gonopods is shorter 

 and broader than in Onychelus. The telopodite of the anterior gonopods 

 short and broad but exceeding the coxal plate; with a conspicuous, digiti- 

 form, distally moderately expanded and rounded process from the mesal 

 or distal edge extending caudad more or less at right angles to the general 



