50 CALIFORNIA ACADEMY OF SCIENCES. 



Abdomen parallel-sided, with a single hair and spine 

 or prickle in posterior angles of segments; whitish with 

 distinct, even, blackish brown submarginal longitudi- 

 nal bands; vulva flatly rounded, with fringe of fine 

 hairs; posterior margin of last segment flatly rounded, 

 with fine, uncolored hairs. 



Physostomum invadens n. sp. 



Specimens from a woodpecker, Melcmerpes ivagleri and 

 from Chiroxiphia lanceolata (Panama). The finding of 

 this species on Melanerpes is the first recorded occur- 

 rence of Pliysostomii7)i on a non-passerine bird. 



Description of female. Body, length 3 mm., width 

 .81 mm; pale translucent brownish with dark brown to 

 blackish head and thoracic markings and lateral ab- 

 dominal bands; in outline and structural characters 

 very like pcdlens. 



Head, length .66 mm., width .6 mm.; almost iden- 

 tical with that of pcdlens; ground color browner; the 

 hairs of ocular emargination rather longer and fewer. 

 Prothorax with lateral angles hardly apparent, but 

 marked by the presence of a long hair and spine. Legs 

 with a little brownish coloring. Abdomen with longer 

 hairs and more in posterior angles of segments, and 

 with two hairs on posterior margin of each segment 

 just a little distance inward from posterior angle. Lat- 

 eral bands of abdomen rather broad and marginal; in 

 each of these broad brown longitudinal bands the 

 true lateral bands, chitinized, may be seen. 



