1182 ON SOME ADDITIONAL LABYRINTHODONT FOSSILS, N. S. WALES, 



depends so much on the age of the individual, that it becomes of 

 minor importance in a comparison between individuals of different 

 ages. The relative position of the orbits, parietal foramen, and 

 quadrato-jugal angles corresponds well enough, especially if we 

 admit that along with the prolongation of the facial bones the 

 articulation of the lower jaw was also gradually thrust further 

 and further to the rear. ' The degree of backward extension of 

 the Quadratojugal varies greatly, according to the species, and, in 

 Archegosaurus, according to the age of the individual.' Miall. 

 I.e., p. 235.] 



The ' Lyra,' consisting of paired muciferous (?) canals running 

 more or less longitudinally along the surface of the cranial bones, 

 is rather obscure and often escapes the eye. It may however be 

 seen upon the left squamosal, near its probable junction with the 

 parietal, and curving slightly forwards and outwards to the 

 posterior margin of the left orbit. I cannot make out whether it 

 is here evanescent or whether it continues without interruption to 

 the place where it may again be made out passing round the 

 inner side of the orbit, and so forwards. The only sutures 

 between cranial bones which I can see (or perhaps imagine) is 

 that between the left post-orbital and quadrato-jugal bones, and that 

 between the right frontal and pre-frontal. The frontal bones are 

 sculptured with shallow longitudinal pits, and similar furrows run 

 from the parietal foramen backwards as has been hinted above. 

 There is no sign of teeth. 



[In Gondwanosaitrus, the dentary piece of the mandible bears 

 a row of small, acute, and subcylindrical teeth. It also laps 

 outward from beneath the jugal and maxilla so that the head is 

 slightly ' underhung' in the same manner as in our specimen.] 



The Vertebrse are all alike, so far as I can see. If the neural 

 spine was ever ossified, it has been removed in the counterpart. 

 The two small knobs, paired right and left, which represent each 

 joint, seem to be the rudiments of the neural arches and trans- 

 verse processes. They exhibit some chalky markings, and other 

 indications of form which may be capable of interpretation by skilled 



