418 STRUCTURE AND CLASSmCATION OF BIRDS 



is a slanting wall of bone (cf. fig. 191 X), present in all the 

 other Steganopodes, co-existing with and lying below the 

 maxillo-palatines, and therefore not comparable to them. 

 True maxillo-palatines, indeed, seem to be only present in 

 Pelecanus of the remaining genera of the family, where they 

 are small and coalesced. The other genera have only the up- 

 wardly sloping bone of Fregata. The vomer too appears to 

 be at the most very small in the higher steganopods, and 

 I have not been able to find it. 



All these facts point to the basal position of Phaeton. 

 It has, however, in the loss of the ambiens departed from 

 the primitive condition. We can derive Fregata from 

 Phaeton ; but in this case the mutual relations of the 

 Steganopodes and the Tubinares, and perhaps the Colymbi, 

 become somewhat obscured. 



As perhaps an appendix to the present group we may 

 consider Odontopteryx toliapicus of the London clay, known ^ 

 by a portion of a skull. 



FtJEBRiNGER discusses this bird very slightly under the 

 Tubinares and Anseres ; both -Gadow and Lydbkkee place it • 

 near the Steganopodes, with which determination I associate 

 myself. The most marked peculiarity of this bird, which 

 has given to it its name, is the serration into longer and 

 shorter teeth of the upper and lower jaw. The two jaws are 

 grooved, which seems to indicate that the beak was, as in 

 the Steganopodes (and other birds for that matter), divided 

 into several pieces. On the right-hand side of the skull is a 

 small notch, which has been identified with the bony nostril 

 of that side. It has, however, in the drawings an accidental 

 look, and the fact of the possible obliteration of the nostrils 

 must be weighed in discussing the steganopodous affinities 

 of the Odontopteryx ; for in many of those birds, especially 

 in Sula and Plotus, the nostrils have been practically oblite- 

 rated. It does not seem to me that the depressed form of the 

 skull, or, so far as we can judge them, the shape of the 

 lacrymals, is strong evidence in favour of the steganopodous 



' Owen, ' Description of the Skull of a Dentigerous Bird,' &a., Q. J. Geol. 

 Soc. 1873, p. 511. 



