426 PROCELLARIIDZ. 
placed upon rocks, but a few were on the tops of stunted sage or on greasewood 
bushes®, The eggs are very similar to those of the European Lesser Black-backed 
Gull (L. fuseus 1°). 
Order TUBINARES. 
The Petrels form a well-defined group of sea-birds, placed by authors variously in 
proximity to the Storks, Penguins, Gulls, &c. Whatever characters the Petrels 
possess in common with any of the above-named birds, the fact remains that they 
are not really closely allied to any of them, but form a group by themselves, the 
peculiar position of the nostrils, which are tubular with an anterior opening, suffi- 
ciently distinguishing them. The bill shows several discontinuous areas, consisting of 
horny plates separated by deep grooves. 
The Petrels are practically cosmopolitan in range, being found very far to the north, 
and also occurring nearly as far south as man has yet penetrated. They include species 
no larger than a Swallow, as well as Albatrosses, with a spread of wing greater than 
that of any other bird. Altogether about 110 species are known. ‘These birds being 
ocean-wanderers, we also include in our enumeration such as have been recorded from 
the Revillagigedo and other islands off the coast of Mexico and Central America. 
Four distinct families of Tubinares were recognized by Salvin in the ‘Catalogue of 
Birds,’ viz. the true Petrels (Procellariide), the Shearwaters (Puffinide), the Diving 
Petrels (Pelecanoidide), and the Albatrosses (Diomedeide). Of these the Peleca- 
noidide alone do not come within the scope of the present work. 
Fam. PROCELLARIIDA. 
In this family the nostrils are united externally above the culmen; the margin of the 
sternum is even; no pterygoid processes are present; the manubrium of the furcula 
is long; the coracoids are long, comparatively narrow across the base and slightly 
divergent ; the second primary is the longest. (Cf. Salvin, Cat. Birds Brit. Mus. xxv. 
p. 342.) 
The Procellariide include two subfamilies—the Procellariing and the Oceanitine. 
Subfam. PROCELLARIINAL. 
This subfamily contains the birds usually called “ Storm ”-Petrels, most of which are 
scarcely larger than Swallows. Salvin has enumerated their characters as follows (Cat. 
Birds, xxv. p. 343) :—*‘* Leg-bones shorter than the wing-bones; tarsus never twice as 
long as the femur; basal phalanx of the middle toe shorter than the next two joints ; 
keel of the sternum entirely ossified; tarsi covered in front with hexagonal scutes ; 
claws sharp and compressed; outer toe shorter than the middle toe; secondaries at 
least thirteen in number.” 
