MONOGRAPH OF THE PETRELS. 



FAMILY L— PROCELLARIID.E. 

 (Salvin, Cat, Birds Brit. Mus., XXV., p. 343.) 



Key to the Sub-families. 



a. 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 13 inches . . 



b. Leg-bones longer than the wing-bones ; tarsus at least 



twice as long as the femur ; basal phalanx of the 

 middle toe as long as, or longer than, the next two 

 joints ; keel of sternum with a large fenestra ; 

 tarsi usually covered in front with a single shield, 

 or with transverse short scutes ; claws usually 

 very flat ; outer and middle toes sub-equal ; 

 secondaries, 10 inches 



Procellariince 



Oceanitince 



SUB-FAMILY I.— PROCELLARIINLE. 

 (Salvin, Cat. Birds Brit. Mus., XXV., p. 343.) 



Key to the Genera. 



a. Tarsus longer than the middle toe and claw ; tail not 



distinctly forked. 



a'. Tail rounded or nearly even 

 b'. Tail wedge-shaped . . 



b. Tarsus not distinctly longer than the middle toe and 



claw ; tail perceptibly forked 



Procellaria 

 Halocyptena 



Oceanodroma 



I. — Procellaria, Linn. 



Procellaria, Linn., Syst. Nat., I., p. 212 (1766) ; Salvin, Cat. 

 Birds Brit. Mus., XXV, p. 343 (1896) 



Hydrobates, Boie, Isis, 1822, p. 562 



Thalassidroma, Vigors, Zool. Journ., ii., p. 405 (1825) . . 



Type 



P. pelagica 

 P. pelagica 

 P. pelagica 



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