NATURAL SCIENCES OF PHILADELPHIA. 141 



vide measurements ; by the very different color of the ripper parts ; and by 

 the fuliginous black instead of white under tail coverts. 



The Puffinus yelcudnus is lighter colored above than is dnglorum, and there- 

 fore this species approaches it in this respect. But yelcuanus is much larger 

 than the present species, and has white under tail coverts like anglorum ; so 

 that it is impossible to confound it with opisthomelas. 



Still more different is this species from the P. nugax, Solander, from the 

 Australian seas. This latter is a very diminutive species, much smaller even 

 than obscurus, the wing being only about 61 inches from the carpus. It also 

 has the white of the throat extending far up on the sides of the head and 

 neck, and white under tail coverts ; characters diametrically opposed to those 

 which obtain in the present species. 



I am acquainted with no other species to which the present bears any sort 

 of resemblance. I trust that I have so fully and correctly indicated its cha- 

 racters and relationships, that its introduction, even into this peculiarly in- 

 tricate .group, will be the cause of no confusion or uncertainty regarding it. 



Two fine examples are contained in the Smithsonian Museum, both col- 

 lected by Mr. John Xantus at Cape St. Lucas, Lower California. (Smiths. 

 Catalogue, Nos. 16,990, 16,991.) 



Puffinus nugax (Solander.) 



Procellaria nugax, Solander, Schlegel, Mon. Proc. Mus. Pays-Bas, 1863, 



p. 31. Puffinus nugax, Bonaparte, Consp. Av., ii. 1856, p. 205. 

 Puffinus assimilis, Gould, P. Z. S., 1837, v. p. 156. Id. Ann. et Mag. N. 



H. xvi. Id. Birds Aust., vii. pi. 56. 

 "Procellaria australis, Eyton," (Bp.) 



Habitat. Australian seas. 



A fine suite of this well marked species is in the collection of the Philadel- 

 phia Academy. Its relationships are closest with P. obscurus, but the dif- 

 ferences are sufficiently obvious on comparison. It is the very smallest 

 known species of Puffinus, being appreciably less than the obscurus. It is 

 hardly 10-50 inches in length ; the wings from the carpus only about 6 ; th 

 tail averages 2-75 ; the bill about one inch ; the tarsus 1 ; the middle toe 

 about the same. The color of the upper parts is about the same as in P. ob- 

 scurus, or a very little lighter ; the feathers generally with appreciably darker 

 tips. A striking diagnostic feature is found in the extent to which the white 

 of the under parts mounts up on the sides of the head and neck, which is 

 greater than in any other species. The inferior caudal tectrices are usually 

 entirely pure white. The under surfaces of the wings are pure white, and 

 the inferior aspect of the inner webs of the primaries are dull whitish, being 

 much lighter than are these parts in obscurus. The bill is dusky horn color. 

 The tarsi are greeenish yellow ; the webs bright chrome yellow. 



The preceding paragraph shows the points in which the species differs 

 from obscurus. It is too distinct from anglorum or ijelcuanus to require com- 

 parison. It cannot be confounded with my P. opisthomelas, since the latter 

 is nearly as much larger than obscurus as nugax is smaller ; has the colora- 

 tion of the sides of the head and neck very different, (compare descriptions ;) 

 has black instead of white under tail coverts, etc. 



I have not an opportunity of examining the original description of nugax 

 by Solander, but all authors agree that it is the species subsequently named 

 assimilis by Gould. I do not know where the species is called auslralis by 

 Eyton, but quote the name on the authority of Bonaparte. 



Analytical Synopsis of the Genera and Species of Puffine;e. 



Family PROCELLARIDJE. 



Subfamily PROCELLARINiE. 



Section Puffineje. 



Char. Tail of twelve much graduated feathers. Bill long, compressed, 



1864.] 



