500 CALIFORNIA ACADEMY OF SCIENCES. 



rufus N. with its numerous varieties belongs to the same 

 species, nine or ten more hawk hosts should be enu- 

 merated. Without doubt this Nirmus type (elongate, 

 with circumfasciate head, broad transverse median ab- 

 dominal blotches, and distinct lateral bands with the seg- 

 mental parts passing the sutures) is not yet at all under- 

 stood. My specimens show the sharp, narrow emargina- 

 tion of the anterior margins of the first and second me- 

 dian abdominal blotches, which has been given as charac- 

 teristic of rufus N. In size, however, the American 

 specimens are distinct from any of the Old World mem- 

 bers of the fuscous group. The female specimen I figure 

 is from a Marsh Hawk, Circus hudsonius, and measures: 

 Body, length 2.4 mm., width .62 mm.; head, length .6 

 mm., width .5 mm. 



L 1 p e u r u s . 



Lipeurus introductus n. sp. (Plate lxviii, figs. 1 and 5.) 

 Six females, two males, and an immature specimen 

 from a Silver Pheasant, Phasianus nycthemerus, received 

 by the Department of Zoology of this University from 

 Mr. A. C. Robison of San Francisco. This Old World 

 pheasant was introduced into America some years ago 

 and it is now breeding wild in parts of the country. This 

 Lipeurus species is of the type of variabilis N. (Giebel, 

 Insecta Epizoa, p. 219, pi. xvi, fig. 3; Piaget, Les Pedi- 

 culines, p. 364, pi. xxix, fig. 4; Denny, p. 164, pi. xv, 

 fig. 6) , showing the characteristic median abdominal 

 blotches with concave sides and the striking sexual dif- 

 ferences; but despite the fact that Piaget finds variabilis 

 an extremely variable form and common to several pheas- 

 ant hosts, I cannot fairly refer my specimens to this spe- 

 cies, because of the much greater size, my specimens 

 being one-third longer than the type forms of variabilis. 



