410 STRUCTURE AND CLASSIFICATION OF BIRDS 



^tli\ 



hinge line separating the 

 cranium from the face. 

 This is present in Pele- 

 canus and Phaeton, while 

 in Phalacrocorax and 

 Plotus the existence of 

 fibro-cartilage allows of a 

 free motion. 



The lacrymal in Fre- 

 gata and Pelecanus is large, 

 with a large descending 

 process, which in both 

 reaches the jugal bar; in 

 addition Fregata has an 

 uncinate bone, which 

 reaches the palatine. Of 

 this there is apparently a 

 rudiment in Phaeton. 



In Phalacrocorax the 

 descending process of the 

 lacrymal completely blends 

 with the ectethmoid to 

 form a ring of bone, as in 

 the Limicolse. In Plotus 

 the same thing occurs, but 

 the lacrymal is much 

 smaller. The interorbital 

 septum as an ossified 

 structure is almost com- 

 plete in Pelecanus and 

 Fregata, largely deficient 

 in Phaeton, almost absent 

 in Phalacrocorax and 

 Plotus. In Phalacrocorax 

 carbo there is a small 

 bonelet resting upon the 

 jugal bar in front of the 



Fig. 191.-SKULL op Fregata. Ventral lopT-vinal • ' thi=i i=i akn 

 Aspect. (After Bedbard.) lacrymai , tniS IS aiSO 



Vo, vomer ; Mxp, maxillo-palatines ; X, upwardly 

 directed part of maxillo-palatineB. 



' Ossiciihcm suprajitgale of Brandt. 



