430 Zoological Society. 



Mr. Waterhouse observed, that the skull in the genera Octodon 

 and Schizodon differs from that of the nearly allied genera of Abro- 

 coma and Poephagomys, as well as the Echymys group, in having a 

 small vertical plate of bone M^hich rises from the upper surface of 

 the anterior root of the zygomatic arch, and which serves to protect, 

 externally, the infra-orbital nerve. The superior incisor tooth enters 

 the superior maxillary bone, and passes beyond the intermaxillary 

 suture by about one-sixth of the whole length of the tooth ; whilst 

 in Abrocoma the incisor is shorter, terminating at the suture men- 

 tioned, and thus approaches the genus Lagotis, as well as in several 

 other characters which he had before noticed. Poephagomys is re- 

 markable for having the superior incisor tooth extended backwards 

 and outwards, covered by a thin fold of bone, and terminating on 

 the outer surface of the palatal portion of the skull, close to the third 

 molar tooth. 



Notwithstanding the great superficial resemblance which exists 

 between these animals and the Muridce, it will be evident upon 

 examination that they belong to a different section of the Rodent 

 order, a section the species of which is readily distinguished, as he 

 had elsewhere pointed out, by the structure of the skull and lower 

 jaw ; it is not, however, in these parts alone that differences exist 

 between the Octodontidce and the Muridce, for there is a dissimilarity 

 in the form of the muzzle, which he should take an early opportu- 

 nity of showing by means of drawings and descriptions, made either 

 from the living animals or from specimens preserved in spirit, and that 

 not only the Octodontidce, but the whole of the great section Hystri- 

 cina, established by himself chiefly upon characters furnished by the 

 crania, possess peculiarities which will serve to distinguish them 

 from other groups of Rodents. In this great section, moreover, we 

 find the tibia and fibula invariably distinct, and not echylosed, as in 

 the Murid(B, which should, I now think, embrace the Myoxidce, but 

 not the genus Anomalurus, which Prof. Wagner is inclined to place 

 in the last-mentioned section, that genus having the tibia and fibula 

 distinct, as in the Sciurine and Hystricine groups. 



Mr. Fraser brought before the Meeting the following species of 

 Chilian Birds, not included in the former collection. (See Ann. Nat. 

 Hist. vol. xiii. p. 498.) 



Milvago megalopterus, Meyen ; Synallaxis flavogularis, Gould ; Stur- 

 nella militaris, VieilL; Attagis Gayi, Less. ; Aphriza Townsendii, Aud. ; 

 Calidris arenaria, 111.; Cyanopterus fretensis, Eyton ; Dafila pyrogas- 

 ter, Eyton ; Dafila urophasianusy Eyton ; Phalacrocorax albigula, 

 Brandt. 



To the last-mentioned bird the following note was attached ; — 

 " Guanayre of the natives. A very scarce bird ; found along the 

 shores of Chile in rocky places. T. B." 



Mr. Fraser also described a new bird from Chile, for which he pro- 

 posed the name of Leptopus Mitchellii*. 



* If the name Leptopus proves to have been previously used, I would 

 propose LeptodactyJus in its stead. 



