1180 ON SOME ADDITIONAL LABYRINTHODONT FOSSILS, N. S. WALES, 



If — as seems reasonable — we consider the relative positions of 

 the posterior angles, the parietal foramen, and the orbits to be of a 

 more permanent character than those which are subjected to 

 continued and increasing differentiation with increase of age, and 

 compare this ' triangulation' with the figures given by Miall 

 (Rept. 1874, p. 192, PL IV.- VII.) we shall discard, as being in 

 these respects remote from our example, the following types : — 

 Mastodonsaurus, Trematosaurus, Metojrias, Brachyops, Rldnosaurus, 

 Loxomma, Batrachiderpeton, Pteroplax, Keraterpeton, and retain 

 Capitosaurus, and even the very elongate Archegosaurus, as more 

 nearly related. Capitosaurus, it will be remembered, is the genus 

 to which the Biloela fossil seems referable. (Archegosaurus, besides 

 its Permian character, can hardly have had its cranial region, 

 even in its youngest forms, and considered apart from its facial 

 bones, so broad and squat as this before us). On the other 

 hand, indeed, if we follow the Tabular View (Miall. I.e. p. 149) it 

 will be placed in Section II., Brachyopina, along with Brachyops, 

 Bothriceps, Micropholis, and Rldnosaurus. Vet, referring to the 

 Analysis of Characters (ib. p. 174) we find the following notes of 

 the mature Capitosaurus combined in this immature example, viz. : 

 — Skull broad ; orbit oval, large, (1) posterior; interorbital space 

 greater than transverse diameter of orbits ; mandible with internal 

 articular buttress (I) ; thoracic plates externally sculptured, lateral 

 plate with reflected process (1). 



These considerations lead us to search among the genera most 

 nearly approaching to Capitosaurus for the adult form of which 

 our fossil is an immature representative. It is very possible that 

 this particular form may be as yet undescribed. But Bothriceps 

 (described by Huxley, Q. J. G. S. XV. p. 647) is Australian, though 

 its particular locality is not known, and therefore has a certain 

 claim upon our consideration. There is only one species known, 

 B. australis, and this seems to differ in some important points 

 from our fossil. For the snout is more pointed (or the head more 



(1) Ambiguous character. The orbit is large in proportion to length of 

 skull, which is a variable. 



