146 PROCEEDINGS OF THE ACADEMY OF 



vrhatever of ashen, gray or plumbeous. The distribution of colors is almost 

 exactly that of the species of Cataractes. 



1 do not think that the plumage above given is that of the adult ; it so 

 closely resembles that of the immature j*E. Lessoni, which is its nearest ally. 

 It is the only one, however, of which we have at present any knowledge. 



I think it most probable that this is a valid species. There is none to which 

 it bears any very intimate resemblance, except Al. incerta and ^E. Lessoni. 

 The relationships of the former will be noticed elsewhere. Compared with a 

 young yE. Lessoni, in which the size and pattern of coloration are not widely 

 diverse, I find them to differ as follows : The upper parts of rostrata are of a 

 deeper, purer brown. The under tail coverts are almost wholly white; those 

 of Lessoni wholly dark colored except immediately about the anus. Rostrata 

 is a smaller bird, the wing being an inch, the tail rather more than an inch 

 shorter ; but the feet are absolutely of the same size, and therefore compara- 

 tively larger. The bills of the two birds are nearly of the same length ; but 

 the radical difference in the character of the nasal tubes, the degree of tur- 

 gidity of the base, and the outline of the feathers, as will be evident on coin- 

 paring the descriptions given, at once distinguish them. 



It is quite possible that some of the indications of older authors may have 

 reference to this species ; but in the utter impossibility of establishing any 

 such with certainty I think it best to assign no synonym whatever. 



iEsTRELATA pakvikostris (Peale) Coues. 



Procellaria parvirostris, Peale, Zool. U. S. Expl. Exp. 1848, p. 298 Cassin, 

 Ornith. U. S. Expl. Exped. 1858, p. 411. G. R. Gray, Cat. Birds Pacif. 

 Isl. 1859, p. 56. 

 Rhantistes parvirostris, Bp. C. R. 1856, lxii. p. 768. 



Habitat. Honden Island. 



As in the case of ^E. rostrata I describe this supposed species from Mr. 

 Peale's type specimen. 



Form. Bill much shorter than the head, but very little less than the tarsus, 

 about two-thirds the middle toe ; slender, compressed, considerably higher 

 than broad at the base ; its lateral outline about straight. Nasal tubes much 

 as in mollis.* A considerable concavity of culmen between the nares and the 

 . elevation of the unguis ; which latter does not rise very high, but is neverthe- 

 less very convex ; much decurved, attenuated and hooked. Sulcus on side of 

 the upper mandible curved, its convexity looking downwards, and greatest 

 near the base of the bill, where the lateral laminae rise high up to embrace 

 the roots of the nasal case. Commissural edge of upper mandible strongly 

 >inuated. Lower mandible almost exactly as in mollis ; perhaps a trifle slen- 

 derer. Outline of feathers on base of bill just as in mollis. 



The wings are exceedingly long, when folded much surpassing the tail. 

 - First and second primaries about equal and longest. Tail of moderate length, 

 contained about '2>\ times in the wing. It is greatly graduated, the difference 

 between the external and median rectrices being 1*25 inches. 



The tibia? are denuded for nearly half an inch. The plates on both sides of 

 the tarsus are small, irregular and very numerous. The tarsus is a little 

 more than three-fourths as long as the middle toe and claw. The usual pro- 

 portionate lengths of the toes prevail. The claws are all small, weak and 

 little curved. The hallux is minute, straight, not very acute. 



Dimensions. "Fourteen inches long, by 36 in extent," (Peale.) Wing 11 ; 

 tail 4*50 ; tarsus 1*25 ; bill 1*08 ; outer toe and claw 1-66. From tip of longest 

 secondaries to end of primaries 4 - 25. Gradation of tail 1'25. 



Colors. Entire upper parts, including both surfaces of the wings and tail, 

 deep fuliginous brown, (with no trace of ashy or plumbeous) becoming almost 

 black on the outer webs of the primaries, and inclining to grayish fuliginous 



* The tubi'H of tie single specimen have been so injured by pressure or otherwise that they 

 cannot now be accurately described. 



[May, 



