REPORT ON THE ANATOMY OF THE PETRELS. 63 
the Tubinares, and in all these forms it is associated with short colic cxca of peculiar 
shape (absent altogether in the Cathartide, as in some of the Tubinares), more or less 
completely webbed feet, tufted oil-gland (except in the Cathartidee), holorhinal nostrils, 
a tendency of the palatine bones to unite behind the posterior nares, truncated mandible, 
broad, strong, well-developed sternum, and strongly curved, well-developed clavicles. 
These birds also agree together in being “ Altrices,” the young birds being quite helpless 
after birth, and requiring to be fed for a long time by their parents—and in generally 
laying eggs of a white, or nearly white, colour. 
The group so constituted, of which the Ardeidee and Falconidze must also be considered 
as aberrant members,—the first family being closely related to the Ciconiide through 
Scopus, whilst the Falconidee are probably, though much more remotely, connected with 
the Steganopods,—corresponds to the Ciconiiformes of Garrod,! with the addition, as he 
had already himself suggested,’ of the Tubinares. 
But his earlier definition of that group, in so far as it relates to the absence in it of 
the accessory femoro-caudal muscle (B), will have to be modified, inasmuch as this 
muscle is, as shown above, generally present in the Tubinares. These too, differ markedly 
from the other Ciconiiformes in the well-developed pectoralis tertiws (very small or 
absent in the others), in the large size of the vomer, and the non-desmognathism of the 
palate, though as regards this latter character it has already been pointed out that the 
Albatrosses are nearly desmognathous, whilst the desmognathism of the Cathartide is 
of a different kind to that prevalent in the other forms concerned. 
The two existing groups of Petrels are clearly related to each other so much more nearly 
than to any other group of birds that it is evident that they must have had a common 
ancestor that possessed the peculiar features characterising the Tubinares as an order. 
Such a form may therefore be safely assumed to have had— 
. The characteristic nostrils of the group. 
. The equally characteristic stomach and duodenum. 
. Webbed feet, with a small hallux of a single phalanx. 
A double great pectoral muscle, and large pectoralis tertius. 
. A formula AB.XY, a gluteus primus and an ambiens muscle. 
. Short colic caeca of characteristic shape. 
. A tufted oil gland, and the pterylosis characteristic of the group. 
8. A holorhinal schizognathous skull, with large depressed vomer, great supra-orbital 
MOAR wD 4 
glandular depressions, no basipterygoid facets, and a truncated mandible. 
9. A short, broad, deeply-keeled sternum, more or less entire behind, with strong 
clavicles. 
10. A peculiar humerus, and tibia with large cnemial crest. 
1 Collected Papers, p. 218. 2 Lor, cvt., p. 521. 
