492 CALIFORNIA ACADEMY OF SCIENCES. 



sented by gracilis, the males of which are .7 mm. long, 

 while the females are .95 mm. long. The arrangement 

 and number of metathoracic hairs are the same as in the 

 females, and the head characters agree. Measurements 

 of the male: Body, length 1.47 mm., width .43 mm.; 

 head, length .34 mm., width .31 mm. 



Nirmus simplex n. sp. (Plate lxvii, fig. 2.) 



Found on a Robin, Merula migratoria (Lawrence, 

 Kansas). It belongs to Piaget's group iiiterruptofasc/a/i, 

 with antennal bands interrupted, with temples tending to 

 become angular, and with the body blotches indistinctly 

 colored. 



Description of female. Body, length 1.77 mm., 

 width .62 mm.; very pale yellowish brown, with darker 

 but inconspicuous markings. 



Head, length .53 mm., width .50 mm.; bluntly trian- 

 gular, the rather narrow clypeal front truncate or very 

 weakly concave; a single short hair in anterior angles 

 and two other shorter ones on lateral margins; trabecular 

 small, acute; eye flat, with a prickle in posterior edge; 

 temporal margins flatly convex, with a single long hair 

 and two prickles just in front of it; occipital margin 

 straight, bare; signature indistinctly colored, broad, 

 emarginate in front and truncate behind; antennal bands 

 distinct, narrow and finely crenate on inner margin; oc- 

 cipital bands indistinct, narrow, extending to posterior 

 rami of mandibles ; temporal margins for a little distance 

 behind eye narrowly bordered; antennae uncolored, fifth 

 segment longer than third or fourth. 



Prothorax short, broad, with lateral margins converg- 

 ing anteriorly; a single strong hair in posterior angles; 

 posterior margin flatly convex; rather broad lateral bor- 

 ders, which extend inward along the posterior margin. 



