244 THE SKULL. [CHAP. xin. 



triangular interval between the diverging premaxillary bars, 

 placed in front of the anterior extremity of the mesethmoid 

 cartilage, on the palatal aspect of the jaw. This bone is 

 not the homologue of the so-called prenasal of the Pig, but 

 " it corresponds with that part of the intermaxilla, which lies 

 between the incisive canal and the mesial palatal suture." 1 

 The infraorbital foramen is very large, corresponding to the 

 large size of the nerves distributed to the sensitive sides of 

 the beak. The periotic has a wide and deep floccular fossa. 

 The mandible has, rather behind the middle of each ramus 7 

 an oblong expansion for a horny tooth, corresponding to that 

 on the maxilla. Behind this it curves gradually upwards to 

 the expanded and transversely extended articular surface. 

 There is no distinct angle, the coronoid process is small and 

 directed much inwards, and on the external surface there is 

 a very deep masseteric fossa. Anteriorly the rami of the 

 mandible have a very slight symphysial connection, in front 

 of which their expanded, flattened terminations again diverge 

 from each other. The apertures for the entrance and for 

 the exit of the branches of the inferior dental nerve are 

 remarkably large. 



1 W. Turner, " The dumb-bell-shaped Bone in the Palate of Ornitho- 

 rhynchus compared with the prenasal Bone of the Pig" (Journ. Anat. 

 Phys. xix. 1885, p. 214). P. Albrecht, " Sur la Fente Maxillaire et les 

 quartre Os Intermaxillaires de 1'Ornithorynque. " Bruxelles, 1883. 



