380 ON THE PETRELS COLLECTED DURING 



is reduced to a short tuft, about half an inch long, of five or six nearly- 

 simple, straight plumes. In the smaller Albatrosses it is larger, and in 

 the rest of the group, including Pelecanoides, it is of good size. 



All the forms have their spaces as well as tracts covered by down- 

 feathers, which may become very long and close-set, especially in 

 Pagodroma. 



The oil-gland is always large, globular, with its surface covered above 

 at the base which is also partly covered by the termination of the 

 uropygial band of the dorsal tract by scattered semi-plumes, and with a 

 tubular mamilla, provided with a good tuft of down-feathers. The tuft 

 and gland are never absent. In the Oceanitidse and smaller forms 

 (Cymochorea, &c.) the tuft of feathers simply encircles the apex of the 

 gland, but in the larger ones it sends a median prolongation across it as well, 

 so as to divide the surface of the mamilla into two lateral parts, separated 

 from each other by the median row of feathers, and each with its opening 

 or openings. The number of these varies in the different forms of the 

 group, as already indicated by Nitzsch (loc. cit. p. 144). Diomedea exulans 

 has about half a dozen small ones in each half, arranged in a crescent. 

 Diomedea brachyura and Thalassiarclie have numerous small apertures 

 opening into a single large circular common opening. The Fulmars, 

 except Aeipetes, have several apertures in each half, as have Daption 

 and Pagodroma, Ossifraga having as many as five. Majaqueush&s four ; 

 (Estrelata three. Aeipetes, Pelecanoides, Bulweria, and the smaller 

 Procellariidee, as well as the Oceanitidae, have apparently only two pores, 

 one in each half of the gland. 



The very young birds, I may remark, are, in all the species I have seen, 

 covered with a thick coating of fluffy grey down, which is pushed off as 

 usual at the ends of the contour-feathers when the latter appear. There 

 are apparently no intermediate changes of plumage, the first plumage of 

 the young bird being similar to that of the adult *, a condition of things 

 very unlike that in the Gulls (Laridse), with which the Tubinares have so 

 often been associated. Besides the long down on the tracts corresponding 

 to the future tracts of contour-feathers, the young birds have a shorter 

 downy covering distributed pretty uniformly, as in the adults, over the 

 intervening spaces, and between the feathers of the tracts. 



Zool. Chall. 2. Alimentary Canal and its Appendages. 



pt. xi. p. 17. The Tubinares as a group agree very closely together in the form of 

 stomach and intestines possessed by them, which have peculiarities not 

 occurring in any other groups of birds, and it is only in the variations in 

 form and structure of the tongue, in the nature of the armature of the 



* Diomedea exulans may be an exception. 



