426 PEOCELLAEIID^. 



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 

 Gu11(Z./mscms10). 



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 (Procellariidae), the Shearwaters (Puffinidae), the Diving 

 Petrels (Pelecanoididee), and the Albatrosses (Diomedeidae). Of these the Peleca- 

 noididsB alone do not come within the scope of the present work. 



Pam. PROCELLARIID^. 



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 Procellariidae include two subfamilies — the Procellariinae and the Oceanitinse. 



Subfam. PROCELLARIINM. 



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 hexau-onal scutes- 

 claws sharp and compressed ; outer toe shorter than the middle toe ; secondaries at 

 least thirteen in number." 



