NATURAL SCIENCES OF PHILADELPHIA. 169 



The broad space between the widely-separated, niutually concave inferior 

 mandibular rami is occupied by soft, more or less distensible skin, naked of 

 feathers, except a small triangular wedge which extends forwards from the 

 base only to a point but a little in advance of the termination of the feathers 

 on the side of the lower mandible. Even this patch does not fill the space 

 from side to side. The feathers on the side of the lower mandible extend as 

 far as the broadest point of the bill. The frontal feathers project a little on 

 the nasa! f^ase. Retreating somewhat, they then stretch transversely across 

 the base ot the lateral laraellip, with no obliquity backwards, to the very edge 

 of the bill ; which is thence densely feathered to the angula oris. 



Bill about as long as the tarsus ; the latter equal to middle toe without its 

 claw; covered with quite regular hexagonal plates, largest antero-interiorly. 

 Outer toe and claw about equal to middle. Tip of inner reaching base of 

 middle. Hallux strong, straight, conical, placed rather low down. Folded 

 wings not surpassing tail. First and second primaries about equal ; last suc- 

 cessively more rapidly graduated. Tail long; two-thirds the wing from the 

 carpus, or contained one and a half times in it; cuneate ; central rectrices 

 acuminately rounded and somewhat projecting; lateral ones more broadly 

 rounded and much graduated in length. 



Prion vittatus (Gm.) Lac^p. 



Proeellaria vidaia, Gmelin, S. N. i. pars ii. 1788, p. 560, and of authors. 



Prion vit/aiiis, Lac^pede, Gray, Gen. Birds, 1849, iii. p. 649, and of later 



authors. 

 Pachyptila vittata, Illiger, Prod., 1811, p. 275. 



Proeellaria Forfteri, Latham, Ind. Orn. ii. 1790, p. 827. Not of Smith. 

 Pachyptila Forsieri, Swainson, Class. Birds, ii. p. 374. Lesson, Traite, 1831, p. 

 613. Jard. and Selb. lUust. Orn. pi. 47. Steph. Gen. Zool. xiiL 1825, 

 p. 251. 

 Proeellaria latiroslris, BonnfertcJ, Ency. Metod. 



Habitat. — Southern portions of both Atlantic and Pacific. 



Line over the eye white. A transocular dusky fascia. Entire upper parts 

 light grajish or plumbeous blue; which color, somewhat diluted, clouds the 

 sides of the breast and the flanks. Edge of wing, lesser coverts, outer vanes 

 and tips of four first primaries, and terminal area on tertials, blackish 

 plumbeous. Inner vanes of quill feathers and tips of tertials fading into 

 pearly or grayish white. Tail concolor with back ; passing terminally into . 

 plumbeous black; which, from an extent of I.} inches on the central rectrices, 

 decreases successively to a bare trace on the outer ones. Under tail coverts 

 white, somewhat clouded with plumbeous. All other parts are pure white. 

 " Bill light blue, deepening into black on the sides of the nostrils and at the 

 tip, and with a black line along the sides of the under mandible ; irides very 

 dark brown ; feet beautiful light blue." [Gould.] 



Dr. Kuhl's fig. 13, and M. Temminck's PI. Col. 528, are by Dr. Schlegel sup- 

 posed to refer to the P. Banksii rather than to this species, contrary to the 

 opinion entertained by most ornithologists. The former figure measures 

 eleven-sixteenths of an inch in width at the widest part of the bill; a 

 dimension which the Banksii is hardly kcown to attain. 



In accordance with the views entertained in the preceding pages, the follow- 

 ing synopsis of the genera and species of the two sections treated of is pre- 

 pared. 



Family PROCELLARIID.^. 



Subfamily Procellariin^, 

 Section JEstrelatcx (Bp. 1855). 



The cutting edge of the upper mandible is not dilated nor furnished with 

 serrations. 



1866.] 



