CHAMBERLIN: HENICOPIDAE OF AMERICA NORTH OF MEXICO. 33 



the ventral edge finely serrate. Basal spines 2+2, flattened distad; 

 conical in broader outline; the inner on each side set more or less at 

 an angle to the outer and its outline in ventral view, presenting its 

 lesser thickness, as a consequence appearing much more slender than 

 the outer. (Plate 4, fig. 4, and Plate 5, fig. 6). 



Gonopods of the male long and with same divisions as in the female; 

 ending in a long, straight and acutely pointed process or claw which is 

 bristle tipped and has its ventral edge serrate, this claw but weakly 

 chitinized. Articles densely clothed with long bristles. Penial pro- 

 cess subcylindric, running to a point at apex on dorsal side. (Plate 5, 

 fig. 8). 



Length 11-13 mm. Males and females apparently not differing 

 in size. 



LOCALITY. California (Mill Valley!). 



Of the ten type specimens, four are males. 



ZYGETHOBIUS COLUMBIENSIS, sp. nov. 



DIAGNOSIS. Dorsum brown ; head dusky ; antennae and legs flavid. 

 Head suborbicular; of nearly equal length and width. Body robust, 

 being only about seven times as long as the width of the eighth dorsal 

 plate; strongly narrowed cephalad as in related species. Antennae 

 long; articles 41, the more loosely joined ones beginning with the fif- 

 teenth, among them being the usual alternation of shorter and longer 

 ones and the last six all being of longer type. Prosternal teeth very 

 small, 3+3. Posterior angles of seventh, ninth, eleventh, and thir- 

 teenth dorsal plates produced. Legs long and slender; tibial spurs 

 present as usual. Claw of female gonopods long and moderately 

 strongly curved ; basal spines very acutely pointed, of moderate width 

 at base. Length 14.5 mm. 



DESCRIPTION. Original color difficult to determine from type 

 specimen. At present the specimen is brown, paler along the median 

 dorsal line. Head dusky. Antennae and legs flavid. 



Body robust, being about seven times longer than the width of the 

 eighth dorsal plate, the tenth plate being nearly of same width as the 

 eighth; strongly narrowed cephalad from eighth plate to the first 

 which is slightly narrower than the head; third plate manifestly wider 

 than the first. Widths of head and first, third, eighth, tenth, and 

 twelfth dorsal plates to each other about as 40:39:45:56:55:52. 

 First plate 1.85 times wider than long; widest a little cephalad of its 



