Vou. II, Pr. IT] LOOMIS—A REVIEW OF THE TUBINARES 23 
age and genital organs in these birds proves that they are 
migrants from the south. On their arrival in spring they are 
in worn plumage and their genital organs are small. During 
the succeeding months they undergo a complete and protracted 
moult, and at the time of the departure of the hosts in autumn 
they are in fine feather with the genital organs in a high state 
of erotic development. Furthermore, the period of absence from 
California waters coincides with the breeding season in the 
South Temperate Zone. In a former paper I have also dwelt 
on this phase of bird migration.* 
The following South Temperate Zone petrels are known to 
occur regularly in the North Temperate Zone during their 
exodus-migration:? Great Shearwater, Cooper’s Shearwater, 
Flesh-footed Shearwater, Sooty Shearwater, Slender-billed 
Shearwater, Buller’s Shearwater, and Wilson’s Petrel. In the 
same category probably belongs the Mottled Petrel, and per- 
haps Stejneger’s Petrel, for both have been secured in numbers 
in the North Temperate Zone. The following have been taken 
there in one or more instances, and may finally prove to be 
regular migrants from the south with fly-lines that ordinarily 
fall short of the Tropic of Cancer: Spectacled Albatross, Cul- 
minated Albatross, Sooty Albatross, Giant Fulmar, Slender- 
billed Fulmar, Cape Petrel, Black-tailed Shearwater, Horn- 
by’s Petrel, Black-bellied Petrel, and White-bellied Petrel. 
Such shorter transequatorial migration appears to obtain 
in the Neglected Petrel, Juan Fernandez Petrel, and Cook’s 
Petrel, all of which have been found more or less numerously 
on the northeastern Pacific within the Tropics. Parkinson’s 
Petrel reaches Galapagos waters, and may yet be discovered 
to extend its exodus-migration across the Equator. 
Migration confined to the Southern Hemisphere is well 
exemplified in the Blue Petrel, Antarctic Fulmar, and Snowy 
Petrel:: 
In the Galapagos Albatross exodus-migration in a direction 
not towards, but away from the Equator seemingly prevails. 
1 Proc. Calif. Acad. Sci., 1900, 3d ser., Zool., v. 2, pp. 303-305. 
2 As migration occurs in every month of the year and in breeding birds of both 
hemispheres, it is apparent that fall and spring migration and southward and north- 
ward migration are inadequate terms; hence exodus-migration and return-migration are 
puberiued for them (cf. Proc. Calif. Acad. Sci. 1900, 3d ser., Zool., v. 2, pp. 
352-354). 
3 Cf. Mon. Petrels, p. 283; Wilson, Nat. Antarct. Exp., N. H., v. 2, Aves, pp. 83, 90. 
