122 PROCEEDINGS OF THE ACADEMY OF 



quential point.* In view of these facts, and deeming it of the utmost im- 

 portance to identify as many of the names of the older authors as possible, I 

 have thought it best to restore Gmelin's appellation. 



Adamastor sericeus Bp. ex Less. 



Pvffinus sericeus, Lesson, Man. Ornith., ii. 1828, p. 402. Adamastor seri- 

 ceus, Bp., Consp. Av., 1836, ii. p. 18S. 



Habitat. Southern Pacific Ocean. 



Sp. char. Bill black; feet flesh-colored, the margins of the webs blackish. 

 Upper parts deep greyish ashy, passing into blackish grey on the upper wing 

 coverts. Head, neck and under parts white ; the former variegated with 

 some touches of clear greyish ash. Circumocular region blackish. Inferior 

 surfaces of the wings of a lighter color than the superior. Tail rounded, its 

 upper surface lightly washed with ashy. 



Length 15 inches ; extent of wings 36 ; wing from the carpus 11'50 ; tail 

 5 ; bill along gape 2-00 ; nasal tubes - 40 ; tarsus 1*75 ; middle toe 1*33. 



The preceding description is compiled from Lesson's original notice. The 

 indications are not as explicit as might be desired ; but I think that there can 

 be no doubt of the propriety of Bonaparte's referring the species to his genus 

 Adamastor. The pattern of coloration is rather that of most of the species 

 of Astrelata ; but the proportions as indicated by Lesson's measurements in- 

 dicate a bird congeneric with Adamastor cinereus. 



I have met with no synonyms of this species requiring notice. 



THIELLUS Gloger. 

 f 



Char. Bill long and slender, about three-fourths the tarsus, compressed, 

 the unguis much decurved, but at base broader than high. Nasal tubes very 

 short, only a fifth of the culmen. Wings of moderate length, and ordinary 

 shape. Tail unusually lengthened, being nearly or quite half as long as the 

 wing from the carpus, very much graduated. Tarsus a fourth longer than 

 the bill, moderately stout, compressed. Middle toe without a claw, a little 

 longer than the tarsus. Of moderate size, rather slender form and uniformly 

 fuliginous colors. 



The most essential character of the genus is found in its unusually elon- 

 gated and much graduated tail. In all other respects it hardly diners at all 

 from Nectris ; and its species have all the same fuliginous hue that charac- 

 terises the latter genus. 



Two species are recognized by ornithologists as belonging to this genus. 

 Though exceedingly closely allied to each other, j-et they seem to constantly 

 differ in some applicable points. 



Thiellus sphenurcs Bp. ex Gould. 



Puffinus sphenurus, Gould, Ann. et Mag. N. H., 1844, lma series, xiii. p. 

 365. Id. Birds Austral., vii. pi. 58. Thiellus sphenurus, Bonap., C. A., 

 1856, ii. p. 201. Procellaria sphcuura, Suhlegel, Mon. Proc. Mus. Pays- 

 Bas, 1863, p. 25. 



Habitat. Australian seas. 



A fine series of these species is in the collection of the Philadelphia Acade- 

 my. The general color of the plumage is a deep chocolate brown, or dark 

 reddish black, most of the feathers of the upper parts with paler margins. 

 The color of the back deepens into pure black on the wings and tail. Below, 

 the general plumage is of a deep brown, with a wash of grey, the brown 

 tinge most palpable on the abdomen, the grey predominating on the throat. 



* I may remark, en passant, that the expression " pres de huit ponces de longueur totale" is 



most probably a typographical error, or a lapsus calami. It was etideutly iuteuded to be " dix 

 huit." 



[April, 



