REMARKS ON THE GENUS SULA. 317 



As to plumage it will be observed that Bonaparte, Gould, 

 Finsch, and Hartlaub describe the adult as having a blackish 

 or brown or grey brown tail, though the latter authors describe 

 what they apparently take to be an old bird with the tail white, 

 but it seems clear that the bird begins by being brown every 

 where, and if two species have not been confounded, (which is 

 not impossible), gradually turns white everywhere, until only 

 the primaries and their greater coverts are brown or dusky. 



For my own part I have very little doubt that two species 

 very similar, but one much larger than the other, are here 

 confounded. 



5A.— Sula. variegata,— Tschudi. Ericbs. Arch. 1843, 

 1.390; Fauna, Peru, 55, 313; Denkschrift, der 

 kais. Akad. d. Wissensch. Wien. II. 2 ; Peru- 

 Reissescizz. I. 327. 



Von Pelzeln. Reise No vara, Vog. 156. 

 ? Brown and white Booby of Latham, Gen. Hist. X. 4U, 

 ? leucophsea, Steph. Gen. Zool XIII., 106, ex Lath : — 

 Tschudi thus describes his species, Cab. J. F. 0. 1856, 188: — 

 i! Head, neck, upper back, and the entire lower surface of 

 the body dazzling white ; the wing and pinion feathers blackish 

 brown on the outer webs, but white on the basal halves of the 

 inuer webs ; lower back, tail, and flanks are besprinkled white 

 and black. In younger birds this besprinkling extends almost 

 over the entire back, the sides, and a portion of the belly. The 

 bill is horny brown ; the feet black ; and the irides deep brown. 

 Guano Islands, Peru." 



Von Pelzeln, loc cit, remarks that he has three specimens of this 

 species, which agree well with each other, only that in one 

 obviously a younger bird, the white borders of the feathers of 

 the back and upper surface of the wings are very little developed ; 

 in fact only feebly indicated ; while on the lower surface and 

 entire under parts from the middle of the breast, the whole of 

 the feathers are of a greyish brown colour, with more or less broad 

 white borders, so that the greater part of the lower surface ap- 

 pears to be irregularly mottled. On the crown and hind neck 

 the white colour is somewhat mixed with brown. The middle 

 tail feathers in the old are entirely, in a younger specimen 

 at their bases, and in another specimen on the inner webs only, 

 greyish white. He gives the following dimensions of these three 

 specimens : — 



B. ah fr. Tr8. Mid Toe (without claw), 



3 92 183 2 56 



3.92 183 256 



411 1 83 275 



Q 16 



