STEGANOPODES 



411 



well developed in Plotus. There are traces of it in Fregata. 

 Another peculiarity shared by Phalacrocorax and Plotus is 

 a style-like bone ^ attached to the occipital, to which the 

 temporal muscles are partly attached. The bone varies in 

 size, is not ankylosed to the skull, and is probably to be 

 looked upon as an ossification in the septum between the 

 two muscles. In these birds also 

 the quadrate is peculiar in form in 

 that the anterior process is short 

 and slender and at right angles to 

 the rest of the bone. 



Sula is nearest to Phalacroco- 

 rax. It has the same peculiar 

 form of the quadrate bone, and 

 the equivalent of the small bone 

 seated upon the jugal bone is 

 apparently there, though anky- 

 losed. The nostrils too are re- 

 duced to a mere pinhole, as in 

 Plotus. The palatines agree ab- 

 solutely with those of Phalacro- 

 corax and Plotus, but the interor- 

 bital septum is not so completely 

 vacuolate. It rises up, more- 

 over, in front, as in Pelecanus, 

 and a faint crest from the pala- 

 tines ascends into the vacuity. 

 The lacrymal is, however, 

 different ; the orbital part is 

 small, but the descending bar is large and joins the jugal ; 

 the ectethmoids appear to be deficient as bony structures. 



Pig. 192.— Skull of Phaeton 

 (atteb Beddabd). Lbtteeing 

 AS IN Fig. 191. 



' J. A. Jei'fkies, ' The Osteology of the Cormorant,' Science, ii. p. 739, iii. 

 pp. 59, 274 ; Gill, ' Osteology of the Cormorant,' ibid. iii. p. 404 ; Shufeldt, 

 ' Remarks upon the'Osteology of Ph. bicrisiatus,' ibid. ii. p. 640, and ' Osteology 

 of the Cormorant,' ibid. iii. p. 143 ; Dollo, Bull. Mus. Roy. Belg. iii. 1884, p. 

 -130. This bone (xiphoid, Yaeeell; nuchal, Mahsh ; intranuohal, Dollo) has 

 been wrongly compared with the post-occipitals of dinosaurs. It is merely a 

 sesamoid. LncAs, ' Description of some Bones of Pallas's Cormorant (Ph. 

 perspicillaius),' P. U. S. Nat. Mus. xii. 1889, p. 88. ' ' . 



