166 Proceedings of the Biological Society of Washington. 



giving the appearance of being finely rugose, the punctae more sparse 

 on metazonites. Sutures deeply impressed. Mesal borders of anal valves 

 protruding prominently. Third legs of male with the usual large uncate 

 process on coxa, the anterior or distal end of hook blunt, rounded. Coxae 

 of next four pairs of legs with smaller, flattened processes which decrease 

 in size in going caudad. Segments forty-two to forty-five in number. 



Length (male), near 58 mm.; width, 7 mm. 



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



Tylobolus castaneus, sp. nov. 



Of a chestnut or, sometimes, of a brighter, cherry red, color, the color 

 in an annulus along caudal border deeper; antennae brown; legs pale 

 brown to fulvous. Aside from the characteristic coloration to be dis- 

 tinguished especially by the structure of the male gonopods. The anterior 

 jnedian plate proportionately much broader than in uncigerus, with the 

 lateral margins evenly convex, not at all angulated as in deses, its apex 

 but little exceeded by the anterior coxal plates which rise in a slight 

 rounded process at the distomesal angle. Antedior telopodites distally 

 narrow, somewhat uncate at tip in the usual way. The telopodites of 

 posterior gonopods narrowed more gradually than usual to an acute 

 point, the distal process scarcely spiniform, not pilose but finely scabrous, 

 short. Cephalic sulcus widely interrupted in the frontal region. Clypeal 

 foveolae 4— J-4. Dental prominences in labral sinus rounded, 3+3. Col- 

 lum narrowly rounded below. Anterior margin a little concave just 

 above lower end, convex on opposite caudal side. Second segment pro- 

 duced below as usual, the ventral margin excavated behind so that the 

 anterior half bulges, the anteroventral corner protruding as a strongly 

 rounded process. Surface of segments roughened by numerous short 

 impressed lines, coriarious. Sutures sharply impressed. Number of 

 segments, forty-seven. 



Length (male), near 40 mm.; width, 5 mm. 



Locality. — California: Brookdale. (R. V. Chamberlin). 



Hiltonius, gen. nov. 



Differs from Sjrirobolus and agrees with Tylobolus in lacking a free 

 inner piece to the posterior gonopods. Differs from Tylobolus in having 

 the telopodite of posterior gonopods erect, not at all uncate and not 

 terminating in a narrow distal process or spine, the mesal margin dentate. 

 Coxal lobes of anterior gonopods tuberculate on anterior face mesally 

 and on mesal face as in Tylobolus. Coxae of third legs of male with promi- 

 nent, distally expanded or somewhat uncate processes; the succeeding 

 four pairs also with coxal eminences, these decreasing in going caudad. 

 Genotype. — H. pulchrus, sp. nov. 



Hiltonius pulchrus, sp. nov. 



General color bright brown with the caudal border of each segment 

 annulate with black; collum bordered with black in front as well as be- 



