GANOCEPHALA 175 



The maxillary (21) which extends from the pre-maxillary to 

 beneath and beyond the orbit, presents a great length, varied 

 according to species and age ; it is of small vertical extent, 

 and terminates in a point, which reaches the tympanic. An- 

 teriorly it unites with the pre-maxillary, and enters into the 

 formation of the back boundary of the nostril ; mesially it 

 unites above with the lacrymal and suborbital, and below 

 forms the outer boundary of the choanal aperture, joining the 

 vomer anteriorly, and the palatine posteriorly. The palatine 

 is a long narrow bone, rather expanded at both extremities ; 

 it forms anteriorly the hinder border of the choanal aperture, 

 and mesially throughout a great part of its extent the outer 

 boundary of the great palatal vacuity. It supports a row of 

 teeth, of which one or two at the fore part are of large size. 



Between the orbit and the maxillary extends an oblong 

 fiat bone (26), forming the lower or outer border of the orbit, 

 uniting with the pre-frontal and lacrymal anteriorly, with the 

 maxillary below, and with the tympanic ( 9 ) and another bone 

 behind. In this position, and in its connections, it agrees 

 with the malar of the crocodile, and also with the suborbital 

 bone or bones of fishes. The latter are unequivocally muco- 

 dermal bones, and may not be the homologues of the endo- 

 skeletal malar bone of saurians, birds, and mammals. To 

 which of the bones, therefore, — suborbital or malar, — the one 

 in question of the Archegosaurus answers, may be doubtful. 

 The writer inclines to view it as a dermal ossification, and to 

 conclude that, as in the higher BatracJiia, the true malar and 

 the zygomatic arch are not developed. Admitting the doubt 

 on this point, the bone (26) may be termed the " suborbital." 



With regard to the next bone (27), the same question, 

 whether it answers to the squamosal in the crocodile, or 

 whether it is a dermal ossification, applies. If a homology 

 with a determinate endo-skeletal bone in the crocodile and 

 higher vertebrates were to be predicated, it would be the 



