6 THE VOYAGE OF H.M.S. CHALLENGER. 
These points are illustrated in the atlas to the Voyage au Péle Sud (pl. xxxii.), the 
classification adopted being explained in the text (vol. ili. 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 (Alle nigricans) of our northern seas. 
1849. Gray and Mitchell, in the Genera of Birds,’ make the Procellariide the fourth 
family of their Anseres. They are subdivided into the Diomedeinz (of one genus) and the 
Procellariinee, of which latter five genera are recognised (Prion, Pelecanoides, Procell- 
aria, Thalassidroma, and Puffinus). The most characteristic generic characters of these 
are figured on plate 178. 
1857. Bonaparte in his Conspectus’ gives a list of the then known genera and species 
of the Procellariide, which he divides into three sub-families, Diomedeinze (Diomedea), 
Procellariinz, and Halodromine. ‘lhe Procellariinee again are divided into five smaller 
groups, designated by letters as follows :— 
A, Fulmarezee— 
Ossifraga, Fulmarus, Adamastor, Daption. 
B. Gstrelateze— 
strelata, Cookilaria, Pterodroma, Thalasseca, Pagodroma. 
C. Prioneze— 
Prion, Halobena. 
D. Procellarieze— 
“*Ungubus compressis”; Bulweria, Oceanodroma, Thalassidroma, Pro- 
cellaria. 
«“**Unguibus depressis” ; Fregetta, Pelagodroma, Oceanites. 
FE. Puffinese— 
Majaqueus, Thiellus, Nectris, Puffinus. 
1866.—In this year Dr. Elliott Coues completed his Critical Review of the family 
Procellariidee 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 Procellariinze, 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 generum avium, tom. 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. 184-197 (parts 4 and 5). 
