96 CALIFORNIA ACADEMY OF SCIENCES. 



meeting on median line ; last segment broadly rounded 

 with several hairs; genitalia pincer-like. 



Docophorus icterodes Nitzsch. (Plate iv, fig. 1.) 



Gemini's Mug. Entomol., 1818, vol. iii, p. 290. 

 Pediculus dentatus Scopoli, Entomol. Carniol., 1763, p. 383. 

 Docophorus icterodes Nitzsch, Burmeister, Handbuch d. Entomologie, 



1832, vol. ii, p. 424; Gurlt. Mag. f. ges. Thierheilk., 1842, vol. 



viii, p. 415; Denny, Monograph. Anoplur. Brit., 1842, p. 101, 



pi. v, fig. 11; Grube, v. Middendorff's sibir. Beise., 1851, vol. 



ii, part 1, p. 468; Giebel, Insecta Epizoa, 1874, p. 115, pi. x, fig. 



8; Piaget, Les Pediculines, 1S80, p. 114, pi. x, fig. 1. 



Specimens of this common parasite of ducks taken on 

 the Surf Scoter, Oidemia perspicillata, the Ruddy Duck, 

 Erismatura rubida, the Red -breasted Merganser, Mer- 

 ganser serrator (Bay of Monterey, California) ; and from 

 the Mallard, Anas boscas, the Greenwinged Teal, Anas 

 carolinensis, the Redhead, Aythya americana, the Lesser 

 Scaup, Aythya affinis, and the Pintail, Dafla acuta (Law- 

 rence, Kansas). Piaget, Giebel and Denny list fully a 

 dozen species of ducks on which icterodes has been 

 found. 



Giebel has described (Insecta Epizoa) three other spe- 

 cies of Docophorus (adustus, p. 113, brevimaculatus, p. 

 114, and brunneiceps, p. 114) found on ducks, and Rudow 

 one species (natatorum, Zeitsch. f. ges. Naturwiss, 1870, 

 vol. xxxv, p. 453), all of which Piaget holds to be syno- 

 nyms of icterodes. Piaget doubts also the validity of two 

 or three other of Giebel's species of duck -infesting Do- 

 cophori. The wide geographical and zoological distribu- 

 tion of the species render variations inevitable, and its 

 abundance on such common birds as ducks renders inev- 

 itable the observation of these variations. 



The measurements of the male specimen figured are: 

 body, length 1.4 mm., width .52 mm.; head, length .44 

 mm., width .4 mm. The species is easily recognizable 

 by its conspicuous rounding, uncolored clypeus with col- 



