CAMBALOID MILLIPEDS — LOOMIS 33 



II. Eyes lacking. 



1. Repugnatorial pores beginning on segment 6; dorsum of 



segments with a weak longitudinal depression on each 



side, leaving mesial portion a little elevated Buwatia Chamberlin 



Repugnatorial pores beginning on segment 5 ; dorsum of 

 segments withovit longitudinal depressions or a median 

 elevation 2 



2. Anterior segments not strongly constricted ; dorsum with- 



out crests Platydere, new genua 



Anterior segments with sides converging backward, form- 

 ing a pronounced neck ; dorsum with definite crests 3 



3. Segment 1 with anterior corners flaring outward away 



from sides of body ; lateral carinae and median dorsal 

 crests produced beyond posterior margins of several cau- 

 dal segments Odachunis, new genus 



Segment 1 with anterior corners not flaring away from 

 body ; lateral carinae and dorsal crests not produced 

 beyond posterior margin, even on caudal segments. 



Pharodere, new genus 



TRIDERE, new genus ' 



Type. — Tridere chelopa^ new species, from southern California. 



Diagnosis. — The strongly mucronate last segment is the most out- 

 standing character, since in no other species in this country does 

 the last segment definitely exceed the anal valves. Also the many 

 scattered setae of the clypeus are unique. 



Description. — Body cylindrical, slender, about 16 times as long as 

 broad; head concealed beneath the enlarged first segment; segments 

 2 to 4 constricted, necklike ; last segment mucronate. 



Head with the vertex sulcate beneath the first segment, the ex- 

 posed surface smooth and shining. Clj^peus smooth above, with 

 numerous scattered setiferous punctations below. Labrum tridentate 

 and with a transverse row of 20 to 24 fine setae. Mandibulary 

 stipes concealed by the first segment, not recessed to accommodate 

 the antennae. Eyes poorly developed and partially covered by the 

 first segment. Antennae (fig. 10, a) inserted in widely separated, 

 deep sockets at the sides of the head, each socket bordered by a raised 

 rim on the upper side and by a projecting lateral corner near the 

 eye; antennae moderately clavate; joints 5 and 6 distinctly thicker 

 than the others ; joints 2 and 6 of nearly equal length, 3 and 5 some- 

 what shorter, but longer than joint 4; joint 7 distinctly projecting 

 and with four olfactory cones. Gnathochilarium as shown in 

 figure 10, h. 



First segment large, concealing much of the head from above, 

 longer than the next three segments together and much broader, with 



^The description and remarljs pertaining to Tridere chelopa were prepared jointly 

 by Dr. O. F. Cook and H. F. Loomis. 



