RALPH V. CHAMBERLIN 191 



Sternites not sulcate. Each one from fourth caudad with four distinct 

 tubercles, one at base of each leg, these conspicuous and subconical on the 

 anterior plates but becoming more and more inconspicuous caudad. In 

 the male the two tubercles present at bases of seventh legs well developed. 

 No conical process on fourth sternite such as described by Pocock for P. 

 tristani. 



Gonopods of male with pro.ximal portion nearly straight, distally evenly 

 curving, first in a cephalomeso-dorsal direction, then dorsad and then back 

 a little caudad of ectad. Distal end broad, laminate. The stile short and 

 rather slender, bending across the laminate division as shown in the figure. 



Length 76 (cf) to 78 mm. ; width of cf type cir. 14 mm. 



Localities. — Juan Viiias: ''Nearer Waterfall" (one male, type, 

 April 26, 1910) ; Reventazon Road (one female, February 15, 1910). 



Seemingly closely allied with P. tristani Pocock from which I 

 separate it chiefly because of the following differences: the 

 greater relative width of the dorsal black band; especially the 

 more irregular lateral margins of the keels which are in some seg- 

 ments conspicuously incised, with the pores larger and uniformly 

 closer to the margin and never removed by as much as twice their 

 diameter excepting in the most caudal segments ; the lack of a 

 conical process on the fourth sternite in the male. There are 

 various other minor differences. The gonopods in the two species 

 are very similar. 



Aphelidesmus calverti sp. nov. 



Anterior portion of metazonites above chocolate brown, posterior border 

 and entire keels yellow. Antennae light brown with seventh joint brown. 



Head smooth. Sulcus across vertex deep, ending at level of antennae. 

 Between bases of antennae a pair of bristles on light spots, a similar but 

 much more widely separated pair midway between these and the labial 

 margin. 



Antennae inserted close together, moderately short, articles in order of 

 length 6, 5, 4; 3 and 2 subequal and but little differing from the fourth. 



. First tergite much wider than head. The anterior and lateral margins 

 together forming a continuous even curve which is subsemicircular, a slight 

 indentation marking point of juncture. Carinae narrowly rounded. 



Anterior corners of all carinae well rounded. Second, third and fourth 

 with an obscure blunt tooth on ectal side near anterior corner which is 

 not eddent on more caudal keels, the edges of which are smooth. Edges 

 of keels in pore-bearing plates thickened, the pore on edge near base of 

 caudal process. Posterior angles of all carinae distinctly produced caudad, 

 spiniform. Surface of all tergites smooth, with no sulci or sculpturing. 



.A.nal tergite of moderate width; sides weakly convex, converging caudad; 

 caudal margin convex, not at all emarginate (see figure). 



TRANS. AM. ENT. SOC, XL. 



