1188 ON SOME ADDITIONAL LABYR1NTHODONT FOSSILS, N. S. WALES, 



These enlarged and altered ribs appear to correspond with those 

 observed in Menojioma, and, the anterior pair, with those of other 

 Urodela, except Proteus and Amphiuma, their distal ends abutting 

 against, and being united by ligaments with the ilia. (Encycl. 

 Brit. s. v. Amphibia, T. H. H.). Nothing appears to be known of 

 the structure of this pelvic girdle in any other Labyrinthodont 

 than Archegosaurus ; and it is interesting to observe the 

 approximation of oar subject in this respect to amphibians now in 

 existence. It is possible that some traces of bone about the distal 

 extremity of the first sacral rib may represent other portions of 

 this girdle. But the supporting rays in both pairs of limbs would 

 seem to have been entirely cartilaginous, since there is no trace of 

 either humerus or femur, which, if at all ossified, would surely have 

 been preserved, inasmuch as the whole animal was evidently quietly 

 buried, and without any mutilation or decomposition. Such limbs 

 could not have supported the creature upon land ; and indeed the 

 slightness and weakness of the pectoral and pelvic girdle tell the 

 same story. It must therefore have been aquatic, furnished with 

 four paddles, but probably depending mainly upon the tail for 

 locomotion. And this perhaps larval condition corresponds with 

 the distinct presence of branchiae, and with its situation as a fossil, 

 in the exact place where it, with the fishes swimming about it, 

 was by some means or other put to sudden death, and covered up 

 with a layer of micaceous mud. 



We may conjecture that animals of this kind, in the toothless 

 condition of their early youth, fed in part at least upon the spawn 

 of the Fishes whose society they seem to have frequented. And the 

 large numbers of the latter which have been found together in the 

 Gosford cutting shows that they used to move about in shoals, a 

 conclusion which also follows from the large numbers recently 

 obtained by Dr. Ramsay, Curator of the Australian Museum, from 

 biickyards near Marrickville, in which the Wianamatta Shales are 

 quarried for the manufacture of bricks. We also see that these 

 fishes, which are all of them Ganoids, lived in quiet lagoons with 

 muddy bottoms, which were formed, in Triassic times as at 

 present, by shifting of the great river courses, and which then, as 



