780 MB. C. AV. AKDIiEWS ON A NEW BIED [JuUe 20, 



The geueral aspect of this skull at once gives the impression that 

 it belonged to a Steganopodous bird, and the details of its structure 

 confirm this view : for instance, the extreme posterior situation oi: 

 the quadrate and the form and position of its orbital process are 

 very characteristic of this group. 



Comparison of this skull with those of other Steganopodes shows 

 that it is sharply distinguished from the skulls of Phalacrocoraa: and 

 Plotus in several points. Thus in these genera — (1) the temporal 

 fossa is much larger and its form and relations are different ; (2) the 

 form of the occipital I'egion is diffei'ent ; (3) the cranial region 

 is greatly elongated, so that the small orbital ]-)rocess of the 

 quadrate is separated from the orbit by a considerable interval ; 



(4) the roof of the skull behind the rostral hinge is not inflated ; 



(5) the interorbital septum is ossified to a much smaller extent. 

 The skull of Sula differs from the fossil in the following points : — 



(1) the temporal fossae are larger; (2) the quadrate is situated 

 somewhat less posteriorly ; (3) the roof of the skull is not inflated 

 behind the rostral hinge ; (4) in the adult the nostril is reduced 

 to a minute foramen. 



There is some similarity between the tvs'o birds in the form of 

 the occipital surface, the degree of ossification of the interorbital 

 septum, and in the presence of a deep temporalis recess. 



Apart from the large size and peculiar form of the beak, the 

 skull of Pelecanus differs from the fossil in (1) large size of orbital 

 process of the quadrate ; (2) the absence of inflated surface behind 

 the rostral hinge ; (3) the complete ossification of the interorbital 

 septum ; (4) the absence of a temporalis recess. 



The skull oiFregata differs in (1) the rather larger temporal fossa; 



(2) the much more complete interorbital septum ; (3) large size of 

 orbital process of quadrate ; (4) absence of rostral hinge ; (5) the 

 depressed form of the posterior portion of the beak and in the 

 small size of the nostrils. 



It is to the skull of Phactlwn that the fossil approaches most 

 nearly. Thus the form oi \\xe foramen magoium and the occipital 

 surface, the structure and relations of the quadrate (as far as can 

 be determined), the form of the cranial region of the skull, the 

 inflation of the anterior portion of the roof immediately behind 

 the rostral hinge, are exactly similar in the two forms. Other 

 points of likeness are to be found in the presence of a temporalis 

 recess and the form of the interorbital septum. 



The chief points of difference are : — (1) in PhaetJton the tempoi'al 

 fossa) are slightly larger ; (2) the skull-roof in front of orbits is 

 rather wider ; (3) the beak is relatively shorter and the nostrils 

 smaller. As to this latter point, however, it is worthy of note that, 

 as Pycraft has pointed out, in a young skull of Phaetlion the uarial 

 openings are \ery much larger than in the adult, and extend back 

 nearly to the rostral hinge as narrow clefts, so that the holorhinal 

 nares of the adult appear as nearly schizorhinal in the young. 

 I have further observed that in some cases, at least, in the adult, 

 ti'aces of the cleft-hke posterior portion of the openings remain 



