62 THE VOYAGE OF H.M.S. CHALLENGER. 
Most previous writers have considered the Petrels as more or less closely connected 
with the Gulls (Laridee), but the grounds for any such collocation are very slight, in my 
judgment, now that the structure of the two groups is better known. 
The Gulls exhibit no trace of any of the characteristic peculiarities of the Petrels,’ and 
differ widely from them in the important feature of being schizorhinal.? The peculiar 
disposition in two quite separate layers of the great pectoral muscle in the Tubinares is 
quite unlike anything seen in the Gulls or their allies, whilst the large pectoralis 
tertius of the Petrels is altogether unrepresented in the Laride. The character of 
the ceca in the two groups is also quite different, and there are no special osteological 
resemblances between the two groups so far as I can see, for the mere schizognathous 
character of the palate is, we now know, not necessarily a mark of affinity. The 
character of the young plumage, the condition of the young birds, and the number, 
shape, and coloration of the eggs—points on which some stress may be laid in questions 
of this kind—are totally dissimilar in the two groups, as indeed are the habits of the 
adult birds themselves, though no doubt both are “ web-footed” and more or less 
pelagic in habit. Such resemblances, however, can hardly be seriously considered as 
indicating any real affinities.’ 
L’herminier, A. Milne-Edwards, and Huxley have all, in describing various points in 
the osteology of the Tubinares, pointed out similarities of various kinds between their 
osseous structure and that of various forms of the Steganopodes, though they still kept 
them close to the Laride. Eyton, on the other hand, places the various Petrels he 
describes in the family “ Pelecanide,” the Gulls forming a separate family by them- 
selves. 
But no one will be prepared, I think, to dispute that the Steganopodes are allied to 
the Herodiones, including under that name the Storks and Herons, with Scopus, only. 
Thus, on osteological grounds alone, there is sufficient ground for placing the Tubinares 
in the vicinity of the Steganopodes and Herodiones. And, in fact, neglecting the 
desmognathous structure of the palate—the taxonomic value of which per se is becoming 
more and more dubious as our knowledge of the structure of birds increases—there is little 
in the characters assigned to the groups Pelargomorphz and Dysporomorphe by Professor 
Huxley (/. ¢., p. 461) that is not applicable to the general Petrel type. 
The completely double great pectoral muscle is a characteristic only found, as already 
observed, in the Ciconiidee, Cathartidee, the Steganopodes (except Phalacrocorax), and 
1 T cannot understand Professor Huxley’s remark (Proc. Zool. Soc., 1867, p. 455) that “the Gulls grade insensibly 
into the Procellariide.” 
* Cf. Garrod, Coll. Papers, p. 128. 
3 No views regarding the affinities of the Petrels other than that to the Laride already discussed, and that to 
the Ciconiiform birds have, so far as I know, been seriously advanced by ornithological writers, Professor Garrod 
having abandoned his early idea that the Tubinares were probably related remotely to the Anseres and their allies, 
(cf. Coll. Papers, pp. 220 and 521). 
