2300 TUBE-NOSED BIRDS, DIVING BIRDS, PENGUINS 



include the Atlantic coasts of Europe, and portions of the shores of the Mediterra- 

 nean, but, according to Mr. Ridgway, it is not known to nest on any part of Amer- 

 ica. The single white egg is deposited in a burrow of considerable length; and in 

 the island of Soa it is stated that the burrows of several pairs often diverge from a 

 common vestibule. 



The small wedge-tailed petrel {Halocypetna microsoma), of the coast 

 5 of Lower California, is the sole representative of a genus distin- 

 guished from the above by the tail being much rounded, the metatarsus exceed- 

 ing the length of the third toe, and by the absence of any white on the rump. 

 Leach's petrel (Cymochorhea leucorrhoa} belongs to an allied genus, comprising 

 several somewhat larger species readily characterized by the deeply-forked tail, 

 in which the feathers have very broad tips, while there may or may not be a white 

 rump patch. The species named has a very wide distribution, being common to 

 both the Atlantic and Pacific. A fourth genus, represented by the fork- tailed 

 petrel (Oceanodroma furcata) and Hornby's petrel (O. hornbyi}, of the North 

 Pacific, differs by the feathers of the forked tail being scalloped at the end, there 

 being no white patch on the rump, and the plumage being either uniform bluish 

 ashy or gray, with the forehead, cheeks, or collar on the throat, and the under parts 

 white. 



The preceding members of the family collectively constitute a sub- 

 1 ^ n family characterized by the presence of at least thirteen secondary 



quills, by the metatarsus being covered with small hexagonal plates, 

 by the sharp and curved claws, and by the leg bones being shorter than the 

 wing. On the other hand, the small Wilson's petrel, together with some allied 

 species, forms a second subfamily distinguished by the presence of only ten 

 secondaries, by the metatarsus being either booted or covered in front with large 

 oblique scutes, by the flat and broad claws, and by the leg bones exceeding 

 the wings in length. In all the group the aperture of the straight nasal tubes 

 is single and circular. Wilson's petrel (Oceanites oceanicus}, which is somewhat 

 larger than the storm petrel, inhabits the Atlantic Ocean and Australian seas; 

 while the other members of the genus are exclusively southern. The general 

 color of its plumage is dusky, with the quills and tail feathers black. As regards 

 their muscles, these petrels are highly specialized, and in the boot-like plates 

 covering the metatarsus, they differ from all other water birds. The white-bellied 

 petrel {Cymodroma grallaria), of the tropical seas, has an even tail, and the 

 metatarsus about twice the length of the third toe, exclusive of the claw. The 

 plumage is parti -colored. 



Like the albatrosses, all the petrels hitherto mentioned are essentially 

 Petrel fly* n a d swimming birds, which dive but little. There is, however, 



a remarkable aberrant petrel inhabiting the straits of Magellan which 

 differs from all the other members of the order in its short wings and diving 

 habits; while it is further distinguished by the nasal tubes being vertical and 

 opening superiorly; the first toe being also absent. This bird (Pelecanoides 

 urinatrix}, which many ornithologists regard as the representative of a distinct 

 family, is, indeed, in habits and appearance so like an auk, that, as Darwin 



