136 Oeological Society. 



The reputed humerus is (he intcrolavicle. 

 „ „ scapula is the humerus. 

 „ „ supra-scapula is the left coraeoid (fig. 2). 

 „ „ „ „ ,, right scapula (fig. 1). 



„ „ right aud left clavicles are the ribs. 

 „ „ right and left coracoids are the pre- coraeoid and 

 coraeoid of the right side. 



Five digits are identified in place of four in 1878. These osteo- 

 logical identifications are iiicousistent with reference of the type to 

 the Labyrinthodontia, and it is accordingly described as a new genus, 

 which is placed in association with Procolophon as a separate family 

 in the tribe Procolophcnia. 



The Author discusses various views which have been expressed 

 with regard to the position of the Labyrinthodonts. He has already 

 separated tliese animals from the Amphibia and combined tliera with 

 the Ichthyosauria in a group of reptiles named Cordyloraorpha, and 

 he enumerates a series of characters which constitute so close a link 

 between the two types ' that it is not possible, in the absence of 

 evidence, to conceive of their being referred to different classes of 

 animals.' 



' But if the order Labyrinthodontia is transferred to the Reptilia, 

 it is then manifest that by includins such genera as Brancliiosaurus 

 and ArcJifgosaio'HS, in which gill-arches are found, it introduces into 

 the Reptilia a character hitherto unknown, and commonly regarded as 

 Amphibian. ... If the osteology of an ordinal type is Reptilian, it 

 cannot be placed in the Amphibia, because two or three genera, or 

 the whole group preserve gill-arches. . . . The Labyrinthodontia may 

 or may not be a homogeneous subclass or order, though the circum- 

 stance that many writers have separated its groups on different 

 principles, and into a varying number of orders, is some evidence 

 that it includes a wide range in character. ... In no part of the 

 skeleton is there a close correspondence between living Amphibia, 

 which are probably unknown before the Tertiary period, and the 

 extinct Labyrinthodontia, which are only known with certainty in 

 the Carboniferous, Permian, and Triassic periods of time.' 



'If the sub-orders of Labyrinthodontia are sub-orders of Reptilia 

 and not of Amphibia, the transition which Pareiasaarus exhibits 

 from Labyrinthodonts to Mammals ceases to be an anomaly.' 



' The close resemblance of form of the bones in the several parts 

 of the skeleton now described with ilonotremata and Anomodontia 

 makes the border-line between Reptiles and Mammals more difiicult 

 to define.' 



The fossil is identified as an Anomodont reptile, chiefly on the 

 basis of resemblance to Procolophon and Pareiasaurus. It is shown 

 not to be a mammal by the large parietal foramen, the composite 

 structure of the lower jaw, and the presence of the prefrontal bone. 

 It differs from known Anoraodonts in making a somewhat closer 

 approximation to Monotreme mammals than has hitherto been 

 evident, aud this correspondence extends to successive segments of 

 both the fore- and hind-limbs. 



