36 PROCEEDINGS OF THE XATION/VL i\IUSEUM vol. 86 



TRIDERE CHELOPA, new species 



Figure 10; Plate 2, Figt-res 6, 7 



Several specimens -were collected beside the road from San Diego 

 to El Centro, Calif., about 2 miles above Mountain Springs, on the 

 eastern desert slope of the mountains, December 10, 1922, by Dr. 

 O. F. Cook. The animals were found lying extended under stones 

 on a hillside of decomposing granite rock. Their movements were 

 slow and when first disturbed formed a close double coil. The type 

 is a male, U.S.N.M. no. 1304. 



After the original collection was made, the type locality was 

 revisited on several occasions, but no further specimens were found. 

 From the dryness of the locality at that time it seemed a very 

 unlikely place for humus inhabitants, but similar places are known 

 in the desert regions of the Southwest where millipeds and other 

 humus animals foDow the soil moisture below ground in times 

 of drought but return to near the surface in seasons when moisture 

 conditions improve. 



Descri'ption. — Length, 30-40 mm; width, 1.8-2.6 mm. Number 

 of segments, 52 to 58. 



Living animals mostly light colored, rather dull pinkish or pur- 

 plish; head and anterior segments much paler; antennae and legs 

 also pale. 



Eyes composed of 10 to 15 rather small ocelli in two rows, forming 

 a transverse, sharply wedge-shaped group, partly hidden beneath 

 the first segment. 



First segment with dorsal surface smooth, the lateral surfaces 

 with tiny scattered granules and a few short, fine, striations directed 

 obliquely downward and forward from the posterior margin above 

 the back corner. Last segment appearing smooth, but slight mag- 

 nification shows a few faint striae and granules; apex of the mucro 

 bearing two setae. Other segments as described under the genus. 



Gonopods as shown in figure 10, / and g. 



Genus CAMBALA Gray 



Head with eyes in a single series ; antennae moderately stout. 



First segment about as long as the next two segments together, 

 not expanded on the sides. 



Body rather slender, the anterior segments not noticeably con- 

 stricted to form a neck behind the head and first segment. One to 

 three segments at each end of the body smooth above, the others 

 with four strong crests between the large poriferous carinae. Pores 

 beginning on segment 5. 



Last segment not projecting beyond the anal valves. 



