426 



ON THE PETRELS COLLECTED DURING 



It is never twice as long as the femur. The tibia is only a little, or not 

 at all, longer than the humerus or manus. 



IV. THE CLASSIFICATION OF THE TUBINARES. 



The propriety of the division of the entire order Tubinares into two 

 main families, which must be termed the Oceanitidae and Procellariidae J, 

 first proposed by Professor Grarrod in 1873 (vide supra, p. 372), has been 

 fully borne out by my further investigations into the structure of these 

 forms. To the differences in the myological formulae, and in the presence 

 or absence of caeca, may now be added numerous other points, both 

 external and internal. 



The Oceanitidae agree together in having the following peculiarities 

 which are not shared in with one or two exceptions marked by an * by 

 any of the Procellariidae : 



The number of secondary remiges is never more than ten. The tarsi 

 are not uniformly reticulate, but are either ocreate, or covered by large 

 Zool. Chall. transversely-oblique scutes anteriorly. The claws are very flat, depressed, 

 Exp, vol. jv. an( j l ame llar. There are no colic caeca.* (Absent in Halocyptena only 

 of the Procellariidae.) There is a peculiar expansor secundariorum muscle. 

 The tendon of the tensor patagii brevis is quite simple throughout. The 



pt xi. p. 55. 



t Imperfect in the specimen measured. This length is estimated. 



