538 bulletin: museum of comparative zoology. 



mally but excavation short and not deep and sometimes concealed; 

 a narrow furrow across base of article. Excavation not always 

 evident, especially in younger specimens. 



Anal legs in male not especially crassate; fifth article at distal end 

 on dorsal surface toward the mesal side with a conspicuous, laterally 

 compressed and longitudinally placed crest which in side view is 

 subtriangular, with dorsal surface convex and caudal end highest. 



Spines of first legs, ^' p' ^ ^ q ; of the second the same as first or ^ q'q'q'q ' 



of the third, ^ ^'q'^' | ; of the fourth, q qq 2 v ^^ ^^^ fifth, q q q'I'I ', of 

 the sixth, ^ ^ ^ ^ ^ ; of the seventh, q' q' ^ ^ I or ventral spines, 0, 0, 0, 2, 2; 

 of the eighth, "' °' ^' ^' ^ or ventral spines 0, 0, 1, 3, 2; of the ninth, 

 q' q' ^' 3 2 or ventral spines 0, 0, 2, 3, 2; of the tenth, ^ ^ ^ 3' 2 ' ^^ ^^^ 

 eleventh and twelfth, ^'^'g'g'^ ; of the thirteenth, oirVs"^' °^ ^^^ 

 fourteenth, °'°'„'^' , , claws 3; of the anal, ' ' ' ' \ or „' ,%' ' , , claws 3, 

 the inner accessory large, the outer one small but distinct. Last four 

 pairs of coxae laterally armed, but none armed dorsally. 

 Length 10-13 mm.; width of tenth plate 1.9 to 2.5 mm. 



Localities. — Mexico; Hidalgo; Guerrero Mills; San Miguel; 

 Pachuca (W. M. Mann). Type, M. C. Z. 1737; eighteen specimens, 

 Type, Paratypes, M. C. Z. 1751, and M. C. Z. 1738, 1739. 



This species is notable for the relatively great width of the body in 

 the posterior region. 



Labrobius delus, sp. nov. 



Dorsum from light to dark brown. Head of similar shade but color 

 typically deeper. Antennae brown proximally, paler distad. Pro- 

 sternum and prehensors clear brown. Venter paler brown, the caudal 

 plates darker as usual. Legs light brown, the posterior pairs a little 

 more brightly pigmented. 



Body moderately narrowed cephalad to the first plate, which is 

 clearly narrower than the plate and much narrower than the head. 

 Widths of head and of first, third, eighth, tenth, and twelfth plates 

 to each other as 74 : 63 : 67 : 80 : 80 : 74. 



Head subcircular. Wider than long in ratio 37:35. Marginal 

 breaks only obscurely indicated. Caudal margin nearly straight or 

 very weakly incurved. The usual median sulcus in front of the suture 

 and two longitudinal ones on caudal portion. 



Antennae rather short. Composed of 29 to 36 articles. Articles 



