NATURAL SCIENCES OF PHILADELPHIA. 141 



These simple facts regarding the varying extension of the dark colors of 

 the head and neck, in a species which otherwise is not known to differ 

 materially in plumage, have given rise to descriptions so worded as to be ap- 

 parently quite in conflict with each other. 



Back a nearly uniform clear bistre brown : but most of the feathers often 

 have slightly lighter margins of an ashen hue. The shade of brown of the 

 back deepens on the wings and wing coverts into blackish brown ; which 

 is especially intense in color on the outer webs of the primaries ; their inner 

 vanes being fuliginous brown. 



The distal half of the tail is like the wings in color : the basal half is white, 

 except the outer web of the exterior feather, and to a less extent some portions 

 of the outer webs of the two next ones. A few of the shortest, most anterior 

 upper tail coverts are colored like the back ; the rest are white. On the sides 

 of the flanks a few feathers are touched with brown. 



The upper tail coverts ; the forehead, lores, sides of head, neck,* under wing 

 coverts, (except the row just along the edge of the wing), axillars and whole 

 under parts are white. 



Bill black ; iris brown ; tarsus, first joint of toes, and contained portion of 

 webs flesh-colored ;t rest of webs and toes, with claws and hallux, black. 



In the young bird, the colors generally are rather darker, and tending more 

 strongly towards smoky brown ; but I have never seen a specimen entirely 

 dark-colored below, though such a state of plumage may be found. The bead 

 and neck all around, and upper part of the breast, may be concolor with the 

 back, as described under the young Lessoni. 



Dimensions. Bill (chord of culmen) 1*45. Nasal tubes - 33, (a little more 

 or less). Height of bill at base '68 ; width *60 ; depth at greatest convexity 

 of unguis -60. Wing (average) 12*00 ; tail 5-50 to 5-75. Tarsus 1-45 : outer 

 toe ami claw 2 , 12; middle do., the same; inner 1*75. Gradation of tail 

 about 1-50. 



The subject of the present article bears an intimate resemblance to no other 

 species of Petrel ; and, on this account, it is the more surprising that its 

 synonymy should have become so involved as it will be evideut is the <ase 

 from the succeeding remarks on its bibliography ; and, particularly, it has no 

 sort of resemblance to the Adamastor cinereus, to which its name of hcesitata has 

 been so often misapplied. Moreover, the species, so far as we know, is not 

 subject to as great changes of plumage as many others of the genus ; its gene- 

 ral aspect, as regards color, is not that of the other congeneric species, but 

 rather of Pvffinus major ; and why, therefore, its synonymy is so involved is 

 a difficult matter to conjecture. 



Bibliography. The first definite reference to this species which I have found 

 is the Proc. hcesitata of Kuhl, as above cited. The description given by this 

 author is entirely pertinent, both as to colors and dimensions ; in fact, some 

 expressions quite exclude any other species. Dr. Kuhl also speaks of his 

 specimen as being "in musaao Bullockiano, nunc in Temminckiano," so that, 

 very probably though I can by no means speak with certainty his bird was 

 the very individual which furnished the subject for PI. Col. 416 of Temminck ; 

 an accurate figure now universally referred to as representing this species. 



At the outset we thus have a very definite starting-point iu discussing the 

 synonyms of this species ; but, most unfortunately, Dr. Kuhl adduces as syn- 

 onyms of his hcesitata two refen-ncesj to Forster's unpublished drawings, and 

 cites Forster as authority for the species. Whereas, neither of these draw- 

 ings refer to the bird now under discussion ; and the first published use of the 



* Neck all around (adults): on sides only (young;) white. 



f Dull yelluwish in the dried state. 



X ' Fo ster, tab. 97 ;" and 'tab. 98, sub nomine rrocellariae leucocephalae." Mr. A. Newton, 

 (Zoologist, x. p. 3696,) tells us that Mo. 97 is the mollis of Gould, called hmsitata : No. 98, the 

 Lessoni of Garnot, called leueocephala ; and without opportunity of examining these drawings, I 

 rely upon Mr. Newton's authority. 



18(36.] 



