152 CALIFORNIA ACADEMY OF SCIENCES. 



Trinoton luridum Nitzsch. (Plate xiii, fig. 4.) 



Germar's Mag. Entomol., 1818, vol. iii, p. 300. 

 (Louse of the Teal) Eedi, Experiments circa gen. Insectorum, 1686, 



pi. xii (or x?); Albin, Nat. Hist, of Spiders and other curious 



insects, 1736, pi. 46 (or 48?). 

 Trinotum luridum Nitzsch. Burmeister, Handbuch. d. Entomologie, 



vol. ii, p. -441; Giebel, Insecta Epizoa, 1874, p. 258, pi. xviii, 



fig. 7. 

 Trinoton luridum Nitzsch. Denny, Mouograph. Anoplur. Brit., 1842, 



p. 234, pi. xxii, fig. 2; Piaget, Les Pediculines, 1880, p. 591, pi. 



xlix, fig. 3. 

 Trinoton gracile Grube. Middendorffs Beise, vol. i, p. 494, pi. ii, 



figs. 6 aud 6a. 

 Trinoton conspurcalum Nitzsch. Gurlt, in Mag. f. d. ges. Thierheilk., 



vol. viii, p. 430, pi. iv, fig. 15. 



I have taken this common parasite of ducks from the 

 Shoveler, Spatula clypeata, the Buff-breasted Merganser, 

 Merganser serrator, the Greenwinged Teal, Anas caro- 

 linensts, the Pintail, Dafila acuta, the Mallard, Anas bos- 

 cas, the Widgeon, Anas americana (Lawrence, Kansas), 

 and from the Ruddy duck, Erismatnra rubida (Monte- 

 rey, California). There is, as has already been said by 

 Piaget, a considerable variation in the individuals of this 

 species, especially in the extent and intensity of the ab- 

 dominal markings. It seems hardly worth while in the 

 present state of knowledge of the Mallophaga to attempt 

 to indicate these varietal differences by name. The size 

 varies somewhat markedly among individuals and the 

 males are smaller than the females. The following are 

 the measurements of two specimens, one a male taken 

 from a Pintail, Dafila acuta (Lawrence, Kansas), and 

 the other, whose measurements are enclosed in paren- 

 theses, a female (the specimen figured by me) taken from 

 a Ruddy Duck, Erismatura rubida (Monterey, Califor- 

 nia) : Body, length 4.3 mm. (5. mm.), width 1.19 mm. 

 (1.56 mm.); head, length .7 mm. (.8 mm.), width 1. 

 mm. (1.28 mm.). 



