6 THE VOYAGE OF H.M.S. CHALLENGER. 



These points are illustrated in the atlas to the Voyage au Pole Sud (pi. xxxii.), the 

 classification adopted being explained in the text (vol. iii. pp. 143-152) published 

 some years later. 



The genus Pelecanoides is expressly excluded from the Petrels by these authors, accord- 

 ing to whom it is closely allied to the Little Auk (Atte nigricans) of our northern seas. 



1849. Gray and Mitchell, in the Genera of Birds, 1 make the ProcellariidaB the fourth 

 family of their Anseres. They are subdivided into the Diomedeinae (of one genus) and the 

 Procellariinse, of which latter five genera are recognised (Prion, Pelecanoides, Procell- 

 aria, Thalassidroma, and Pufftnus). The most characteristic generic characters of these 

 are figured on plate 178. 



1857. Bonaparte in his Conspectus 2 gives a list of the then known genera and species 

 of the Procellariidae, which he divides into three sub-families, Diomedeinse (Diomedea), 

 Procellariinse, and Halodrominse. The Procellariinse again are divided into five smaller 

 groups, designated by letters as follows : — ■ 



A. Fulmarese — 



Ossifraga, Fulmarus, Adamastor, Daption. 



B. GCstrelatese — 



(Estrelata, Cookilaria, Pterodroma, Tlialassceca, Pagodroma. 



C. Prionese — 



Prion, Halobcena. 



D. Procellariese — 



"*Unguibus comp>ressis" ; Bulweria, Oceanodroma, Thalassidroma, Pro- 

 cellaria. 

 "**Unguibus depressis" ; Fregetta, Pelagodroma, Oceanites. 



E. Puffinea? — 



Majaqueus, Thiellus, Nectris, Puffinus. 



1866. — In this year Dr. Elliott Coues completed his Critical Review of the family 

 Procellariidge commenced in 1864. 3 



This is the most complete account yet published of the synonymy and distribution of 

 the species of this group, which is divided into 24 genera, containing 92 species 

 (17 of these being doubtful). Following Bonaparte, the same three sub-families are 

 adopted, the Procellariinse, as before, being subdivided into five groups. 



The genera composing these are as follows : — 



Section Procellariese — 



Oceanodroma, Cymochorea, Halocyptena (gen. nov.), Procellaria, 

 Oceanites, Fregetta, Pelagodroma. 



1 Loc. cit., iii. pp. 646-650. 2 Conspectus generuni avium, torn. ii. pp. 184-206. 



3 Proc. Ac. Nat. Sci. Philad., 1864, pp. 72-91 (part 1), and pp. 116-144 (part 2) ; loc. cit., 1866, pp. 25-33, 

 (part 3), pp. 134-197 (parts 4 and 5). 



