54 



THE VOYAGE OF H.M.S. CHALLENGER. 



(except in Procellaria where it is just) but shorter, and the same is always the case 

 when it is compared to the ulna. 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 ProceUariidse, 3 first proposed by Professor 

 Garrod in 1873 (vide supra, p. 9), has been fully borne out by my further investigations 

 into the structure of these forms. To the differences in their 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 uni- 

 formly reticulate, but are either ocreate, or covered by large transversely-oblique 



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



2 Cf. Proc. Zool. Soc, 1881, p. 737. 



