72 CALIFORNIA ACADEMY OF SCIENCES. 



slight but distinct emargination of the lateral margin in 

 front of the ocular emargination, being about where the 

 projecting palpi pass the margins of the head; head wider 

 than long, temples expanded and angulated in front and 

 behind; antenna; short and entirely concealed in their 

 cavities; palpi rather long and projecting beyond mar- 

 gins of the head ; prothorax hexagonal with obtuse an- 

 gles; the mesothoracic suture slightly indicated on the 

 lateral margins; legs long and only slightly colored, 

 first tarsal segment very short with a small acute lobe, 

 second segment larger; abdomen similar in the sexes, 

 obovate, widening posteriorly, with broad lateral bands. 

 Color tawny, blotches ferrugineous, and lateral bands 

 dark reddish brown. Only one species certainly known; 

 found only on the chimney swift. 



Genus Anchtrona Westwood. (Plate xiii.) Body very 

 large, 6 mm. long and 2^ mm. wide; head crescentic, 

 without ocular emargination; with two 2-pointed strongly- 

 chitinized processes on ventral aspect of hind head pro- 

 jecting backward beyond occipital margin of the head; 

 antennae concealed in ventral cavities; the lateral palpi 

 short. Prothorax as large as the head; the metathorax 

 like an abdominal segment; the coxae of the front legs 

 bear a long appendage or lobe; abdomen of ten seg- 

 ments. Only a single species certainly known; found 

 on the Fulmars. 



Genus jMcnopon Nitzsch. (Plates xiv and xv.) Body 

 small to large, varying from 1 mm. to 5 mm. in length; 

 of general shape and character of Colftocefihalitni (from 

 which it is sometimes hardly distinguishable), but the oc- 

 ular emargination is wanting or is slight; an ocular emar- 

 gination is often present and plainly visible inferiorly, but 

 superiorly there is a membrane which extends across it; 

 head always widest across the temples; the antennae 



