NATURAL SCIENCES OF PHILADELPHIA. 29 



with equal reason they might be held as indicative of the extreme of varia- 

 tion of a single changeable type, and thus forming only a local race or geo- 

 graphical variety. 



The Procellaria glacialis of Pallas in all probabilty refers to this species 

 rather than to the'true glacialis of Linnaeus. I also think that the "Procel- 

 laria glacialis, juniores ex America Septentrionali allatre, colore cineraseenti- 

 fuliginoso tincta) " of Kuhl's "Beitrage," p. 141, belongs here rather than to 

 the Thalassoica glacialoides to which Dr. Schlegel has referred it. 



Fulmarus Rodgersii Cassin. 



Fulmarus Rodgersii, Cassin, Cat. Birds North Pacif. U. S. Expl. Exped., in Pr. 

 A. N. S. Ph. 1862, p. 290. 

 Habitat. North Pacific Ocean. 



I have before me Mr. Cassin's original and type specimen. With exactly 

 the size and very nearly the form of F. glacialis, it differs from the latter 

 very decidedly in color, as will be seen by the following comparative de- 

 scription : 



The bill is bright yellow, except the base of the unguis of the upper man- 

 dible, which is bluish black. The middle of the back, the scapular feathers 

 and some of the lesser wing coverts are a rather dark grayish ash, approach- 

 ing the hue that is most distinctive of pacijicus. The rump and upper tail 

 coverts are pure white. The rectrices are fuliginous grayish ash ; their inner 

 webs and their extreme apices whitish, their shafts wholly yellowish. The 

 whole of the tertials and the greater wing coverts are pure white ; the lesser 

 wing coverts and edge of the wing of the same color, but marbled with the 

 ashy hue of the back. The secondaries are white with yellow shafts; the 

 terminal half of their outer webs grayish brown. The primaries are dull 

 brownish black, their entire shafts yellow, their inner webs to within an 

 inch of their tips white. These markings of the primaries are much like 

 those of Thalassoica glacialoides. All the rest of the body is white. The 

 legs and feet are bright yellow ; the outer aspect of the tarsus, aud the outer 

 toe somewhat obscured by dusky. The nails are ochraceous brown. 



Bill along chord of culmen 1*50 inches and hundredths ; from feathers on side 

 of lower mandible to its apex 140; nasal tubes *60 ; height of bill at base *80 ; 

 width about the same ; wing from the carpus 1225 ; tail 5*50 ; exterior 

 rectrices - 75 shorter; tarsus 2-00 ; middle toe and claw 2-60 ; inner do. 220. 

 Some differences in the shape of the bill of this species are readily recog- 

 nizable. It is even stouter than that of glacialis, being at the base fully aa 

 wide as high ; and the lateral lamina? of the upper mandible is bulging and 

 convex rather than straight. The nasal tubes are larger, broader, more 

 depressed, with no traces of median longitudinal carination. Independently 

 of these discrepancies, it is to be distinguished from glacialis by the restric- 

 tion in extent and deep hue of the color of the back ; by the white tertials 

 and coverts, dark rectrices, yellow primary shafts, amount of white on inner 

 webs of primaries, etc. 



But a single specimen is known to exist in any collection. No. 21304 of 

 the Smithsonian Register. From the North Pacific, the precise locality not 

 known. 



THALASSOICA Reich. 



Procellaria sp. auctorum. 



Thalassoica, Reichentiach, Syst. Av. Type P. glacialoides, Smith. 



Priocella, Homb. et Jacq. Same type ; fide Gr. R. Gray. 



Gen. char. Bill slightly shorter than the head, or tarsus, about three- 

 fifths the middle toe and claw ; higher than broad at the base, compressed, 

 not very robust, its sides regularly tapering to the rather thin tip. Unguis 

 attenuated and only moderately hooked ; commissure a little curved, outline 

 of inferior mandibular rami, and of gonys, both slightly concave. Nasal 



1866.] 



