1898.1 OSTEOLOGY OF BIUDS. 91 



The pehic limb of the Steganopodes is peculiar in having a long 

 hallux directed forvvai-ds — which, in the living bird, is embraced 

 with the remaining digits in a common web. The tibio-tarsus is 

 inflected distally as in Anseres, some Rallidce, and Spheniscidce. 



The tibio-tarsus of Phaiithon may be readily distinguished from 

 that of either of the groups just mentioned by the feeble develop- 

 ment of its cnemial crests. In the remainder of the Steganopodes 

 the tibio-tarsus can be readily distinguished from that of either the 

 Anseres or RallkUe by the great length of the fibula. This, 

 however, does not apply to the Spheniscidm, in which the fibula is 

 also very long ; from that group the Steganopodes can be at once 

 distinguished from the fact that there is a considerable space 

 always visible between the fibula and the tibio-tarsus, running 

 from the lower end of the fibular ridge to the point where the 

 fibula joins the distal end of the tibio-tarsus. 



The tarso-metatarsus of Fregata resembles that of the Penguins, 

 the three metatarsals being more or less distinct and separated by 

 grooves one from another. It may, however, be readily distin- 

 guished therefrom by the fact that the 2nd trochlea is longer than 

 the 3rd and is directed backwards ; and by the presence of a 

 foramen between the 3rd and 4th trochleae. 



The tarso-metatarsus in all save Fregata is marked by a fossa at 

 the proximal articular end of the anterior surface into which open 

 foramina, pneumatic or otherwise. The hypotarsus is complex in 

 all. Save in Phaeihon and Fregata, it is characterized by the 

 considerable development of the gastrocnemial ridge. 



The object of this paper Mas to show that the Steganopodes 

 must be regarded as a natural group. Taking Phalacrocorax as its 

 type, a fixed point will be gained by which to measure, roughly, the 

 amount of specialization which the various members have under- 

 gone. Plotus may perhaps be regarded as having passed beyond 

 the mean, it is a highly specialized Cormorant ; Sula has about 

 reached the lev'el of Phalacrocorax -. Pelecanus, though possessing 

 the peculiar palate of Phalacrocorax and Sula, is in most other 

 I'espects less modified ; Fregata and Phaethon are the lowest members 

 of the group, they represent two divergent branches of a common 

 stem. Sula, on account of the form of its basitemporal plate, 

 seems to have affinities with Fregata (PI. VIT. fig. 1); Pelecanus, 

 for similar reasons, with Phaethon (PL VII. fig. 2). All, save 

 Phaethon and Fregata, have lost the vomer. Piirbringer and Gadow 

 both agree in regarding Phaethon as the most aberrant of the sub- 

 order, and Mr. Beddard goes perhaps further . he writes (1) : — ■ 

 " So different are the skull chai-acters of Phaethon from those 

 of the typical Steganopodes that, were it not for Fregata, the 

 bird would have to be ignominiously expelled from the order. 

 This catastrophe is averted by Fregata, the skull of which, as will 

 have been gathered from the foregoing remarks, serves to link 

 Phaethon with the Cormorants, Gaunets, and Pelicans." I cannot 

 but feel, however, that, taking all the skeletal characters into 

 consideration, this family is much more closely allied to the 

 Steganopodes than to that of any other Order. With this the 



