ATOPETHOLID MILLIPEDS — HOFFMAN AND ORCUTT 115 



intersegmental membrane or held apart by a median distal projection 

 of the sternite, produced proximally into conspicuous coxal apodemes; 

 telopodite typically small and largely concealed behind the coxites in 

 anterior aspect. Posterior gonopods rather small, concealed within 

 a gonocoel formed by the anterior pair; their apodemes long and 

 slender, reaching dorsal side of pleurotergite, loosely jointed with the 

 transverse basal coxal element; telopodite usually fused with the latter 

 at a right angle. Posterior gonopods set transverse to the longitudinal 

 body axis, but not connected by a sternal remnant. 



Head small, clypeal foveolae 3-3 to 5-5, var3dng within a species; 

 ocellaria of normal size, ovoid to rounded, with 30 to 50 ocelli in each; 

 antennae variable in length, held in a depression in the face of the 

 mandibular stipe, with 4 terminal sensory cones. 



Collum wider than head, laterally acuminate, the anterior lateral 

 edge set off by a distinct groove. Second segment usually about as 

 long as collum but not produced forward under its tip, the pleural 

 element produced mesiad, its anterior edge usually elevated as a 

 distinct flared margin. Sm-face of tergites smooth or very finely 

 punctate in most species ; in some species the lower sides are adorned 

 with longitudinal striations that may be produced beyond the 

 caudal edge of the segments in the form of acute spinulae. Tergites 

 with two transverse sutures, a median dorsal suture, and a lateral 

 suture on each side at level of the ozopores, the ozopores opening in 

 the mesozonites except in the subfamily Arinohnae. Rudimentary 

 scobinae occur in at least one genus (Scobinomus) . Anal tergite blunt, 

 rounded, shorter than valves; latter inflated, their inner margins 

 meeting at a reentrant angle and provided with a comb of fine, closely 

 set bristles, otherwise glabrous. Preanal scale usually broadl}^ eUip- 

 soid, nearly flat, but occasionally modified shghtly (Centrelus). Legs 

 moderate in length, the sixth joint longest, ventral macrosetae of 

 legs apparently constant within a genus, varying from 1-2-2-2-2-6 

 to 1-1-3-3-3-8. Sternites rectangular to trapezoidal, usually widest 

 in front, with 6 to 12 or more transverse ridges or striae. Coxal lobes 

 of anterior legs variable, from small conical productions to elongate 

 and speciahzed structures, those of the third pair usually largest, 

 extending caudad over or between those of the following pair. Tarsal 

 claws of the third to sixth legs may be normal, rudimentary, or 

 hypertrophied, their form a specific rather than generic character. 



The genera that we have been able to recognize fall into four natural 

 groups probably worthy of subfamily rank although some appear 

 to be much more differentiated than others. These groups may be 

 characterized by the following key: 



