224 AUSTRALIAN AND POLYNESIAN LAND AND MARINE MOLLUSCA, 



We have in this jaw a diastema unlike that of any known 

 inacropod, but having its greatest similitude in Sthenurus. It is in 

 the latter genus again that we find some approach to the greatly 

 dilated incisor in the mandible before us. It has already been 

 observed that the symphysis is that of Sthenurus rather than of 

 Macropus on the one hand, or of the more aberrant macropod, 

 Procoptodon, on the other. Concomitant with these indications of 

 alliance with Sthenurus, we find however, a premolar departing 

 from all others of the family. It seems, therefore, reasonable to 

 surmise that Palorchestes was on the whole a true saltigrade of 

 the macropodal type, and that the point of divergence whence its 

 differentiation commenced, was Stlienurus or some form closely 

 allied to it. The use to which the determination of such relation- 

 ship may be put, is best known to those who have to deal with 

 the disconnected bones of the numerous extinct species of 

 kangaroos; without its guidance their identification, always 

 doubtful in some degree, becomes the most unsatisfactory guess- 

 work. 



Synonymy of Australian and Polynesian Land and Marine 



Mollusca. 

 By J. Brazier, C.M.Z.S., &c, &c. 

 1. Patella aculeata. 

 Patella aculeata, Reeve, Conch. Icon., pi. 32, sp. 90. 

 ,, squamifera, Reeve, Coc. cit , sp. 94. 

 ,' aculeata, Angas, Proc. Zool. Soc, p. 221, 1867. 

 „ squamifera, Angas, loc. cit., p. 221, 1867. 

 ,, aculeata, Tenison-Woods, Proc. Roy.Soc.Tas., p. 22, 1877, 

 Bab. — Port Jackson near the Heads, and outside from the 

 Clarence River on the north, to Twofold Bay on south ; it is also 

 found in Tasmania. 



I have had some hundreds of specimens of the so-called species 

 squamifera, but I can only identify them with aculeata. The very 

 rough sculptured variety is of very common occurence at tho Old 



