572 MK. R. LYDEKKER ON LOWER JAWS OF PROCOPTODON. 



Three species — P. Goliah^ 1\ liaj^Jui, and P. Otuel — were, there- 

 fore recognized in the ' Catalogue.' The third being much smaller 

 and totally different from either of the others will need no further 

 notice here. 



With regard to P. Goliah and P. liajplia, it appeared to me that 

 the latter was mainly distinguished from the former by its inferior 

 dimensions, and it was accordingly suggested that the one might 

 prove to be merely a smaller race of the other. 



Recently I received, among other specimens, from the Commis- 

 sioners of the Exhibition of the Mineralogical Products of New South 

 Wales (held in the summer of 1890 at the Crystal Palace), two 

 mandibular rami of Procoptodon obtained from the clay-beds near 

 Miall Creek, in the neighbourhood of Bingera, on the northern fron- 

 tier of jN'ew South Wales *. These specimens evidently belonged to 

 two large-sized species of the genus, and I have accordingly been led 

 to reconsider the evidence as to the specific distinctness of P. Raplia 

 from P. Goliah. The result of my comparison of these specimens 

 with the lower jaws in the British Museum is to show conclusively 

 that this part of the skull indicates two very distinct species of large 

 Procoptodons : but that there is the almost insuperable difficulty of 

 determining to which of the two species they should respectively be 

 referred, assuming that the types on which these species were estab- 

 lished are specifically distinct from one another. I also conclude that 

 differences of size are of very little importance in the discrimination 

 of the two species, — both types of lower jaw indicating larger and 

 smaller individuals, which may represent either sexual or racial 

 differences. 



I will first take the left ramus represented from the inner side in 

 PI. XXI. fig. 1. This specimen shows the whole series of cheek- 

 teeth, which have been proved to be the permanent ones by chiselling 

 away the outer side of the jaw below the first molar, and thus re- 

 vealing the absence of a replacing ]3remolar. The extremity of the 

 symphysis is wanting ; and the greater part of the hinder region is 

 unfortunately absent. This specimen is characterized by its great 

 depth, especially at the anterior extremity ; and also by the deep and 

 distinct channel between the last two molars and the ascending 

 ramus. The characters of this mandible are very similar to those of 

 the right ramus figured by Sir Richard Owen in the Phil. Trans, for 

 1874, pi. Ixxvii., as P. Raplia (cast, B.M. N'o. M. 3676), although 

 the Bingera specimen is somewhat the larger. The British Museum 

 possesses another and almost entire mandible f (N^o. 46836) of the 

 same type, which is of extreme importance as aftbrding specific 

 characters. The dimensions of these three specimens are as 

 follows :— 



* An account of these deposits will be found in the Proe. Eoy. Soc, vol. xlix. 

 pp. 61, 62. 



t Figured in Owen's ' Extinct Mammals of Australia,' pi. cxxviii., as P. Ba/pha. 



