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



stripping or disappearance of the dorsal region may I suppose 

 be due to the cartilaginous condition of the notochord. 



It is strange that no vestiges of limbs can be made out. But 

 they may have been detached with the aforesaid dorsal structux*es, 

 and escaped observation when the stone was split in the quarry. 



No. 2, from the inversion of the orbit ring, which is deeply 

 sunk, instead of projecting boldly as in the other specimens, 

 appears to be a cast of the upper surface of the head. But the 

 paint with which it has been covered renders it difficult to feel 

 certain upon this point. Radiating sculpture marks the centres 

 of four of the bones, but their sutures are not to be discovered. 

 They may perhaps be the Maxillaries and Premaxillaries. 



The principal measurements are as follows : — 



Dimensions of Head. 



No. 1. No. 2. 



Length Uncertain; perh. about 65 mm. pevh. about 72 mm. 



Breadth Ditto, ditto 55 Ditto 62 



Distance of orbit from base of skull 15 Ditto 25? 



Least width of interobital space 10 6 



Length of orbit 13'5 14 



Width 12 12 



Distance of parietal foramen from base 



of skull 12? 12 



From centre of occiput to posterior end 



of orbit 21 22-5? 



From tip of snout to anterior end of 



orbit 37 37 



Thoracic Plates. No. 1 only. 



Medial. Length 43 mm. 



Greatest breadth 27 



Centre of radiating sculpture in advance of gi'eatest breadth by... 7 



Length of each anterior margin 32 



Length of each posterior margin 19 



Laterals. Length from exterior angle (centre of radiation) to 



anterior margin 27 



Transverse breadth of the whole set from angle to angle 36 



It is not absolutely certain that these two fossils belong to the 

 same species as that first described. But they appear to show no 

 other differences than such as are known to be brought about in 

 other genera of Labyrinthodonts by length of life and increase in 

 size ; and I therefore, provisionally at any rate, regard them as 

 the same. 



