April 26, 1831. 



Joshua Brookes, Esq. in the Chair. 



Mr. Vigors exhibited, from the collection of Mr. Leadbeater, an 

 undescribed species of Cockatoo from New Holland, and pointed 

 out its distinctive characters, which may be expressed as follows : 

 Plyctolophus Leadbeateri. Plyct. alius; genis, collo in 

 fronte, pectore, tectricibus alarum inferioribus, abdomineque 

 medio roseo-tinctis ; cristce elongatce occipitalis plumis basi roseis, 

 apice albis, macula Jlavd in medio notatis; pogoniis remigum 

 rectricumque internis roseis, illorum saturatioribus. 

 Statura Plyct. sulphurei, Vieill. 



Eleven species of Chcetodons, forming part of the collection of 



Fishes from the Mauritius presented by Mr. Telfair, were laid on 



the table. Seven of these were referable to the genus Chcetodon as 



restricted by M. Cuvier; and among them Mr. Bennett pointed out 



more particularly the Chcet. strigangulus, Sol.; the Chcet. vittatus, 



Schn.; the Chcet. Lunula, Cuv. & Val. ; and two species which he 



believed to be new to science, and which may be thus characterized : 



Chmt. flavescens. Chcet. Jlavus ; ore, fascia oculari, linea 



pinnas dorsalem analemque postice ambiente, apiceque pinnarum 



ventralium nigris ; lateribus argenteo vittatim guttulatis , pinna 



caudali recta, apice late hyalino. 



D. 44. A. T v> &c. 



Affinis, ut videtur, Chcet. virescenti, Cuv. & Val. Differt colore 

 flavo ; pinnis verticalibus postice nigro tenuiter cinctis ; lateribus 

 obscure argenteo-guttulatis. 



Chjet. Zoster. Chcet. brunneo-niger ; zona lata media ventreque 

 argenteis ; pinnd caudali recta albd : Jascid oculari nulla. 



p. n. a. w. P. 17. C. 15. V. * . 



The remaining species exhibited types of the genera Heniochus, 

 Cuv.; Zanclus, Cuv. & Val.; Holacanthus, Lacep. ; and Platax, 

 Cuv. : the Heniochus being the species recently described by 

 MM. Cuvier and Valenciennes as the Hen. monoceros. In this 

 individual the spine in front of each orbit is strong, almost equalling 

 the single spine which projects from the middle of the slope of the 

 head ; and the whole contour of the anterior part of the fish ap- 

 proaches very nearly to that of Taurichthys, Cuv. & Val. ' 



Mr. Gray exhibited several living specimens of the Rana Ru- 

 beta, L., the Natter-jack of Pennant, a reptile intermediate in form 

 and habits among the British Amphibia between the Toad and the 

 Frog. He stated that this animal, the indigenous existence of 

 which has frequently been doubted, is found abundantly on Black- 

 heath, and on other commons in the neighbourhood of London. 



[No. VI.] Zool. Soc. Proceedings of the Comm. of Science. 



