April26, 1831. 



Joshua Brookes, Esq. in the Chair. 



Mr. Vigors exhibiteil, 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. albus ; genis, colio in 

 Jronte, pectore, tectricibus alarum inferioribus, abdomineque 

 medio roseo-1 indis ; cristce elongatce occipitalis plumis basi roseis, 

 apice albis, macula Jlava in medio notatis ; pogoniis remigum 

 rectricumgue internis roseis, illorum snturatioribus. 

 Statura Pli/ct. 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 vvere referable to the genus Chatodon as 

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

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

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

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



Chjet. flavescens. Chcet . Jlavus ; ore, fascia ocidari, linea 

 pinnas dorsalem analemque postice ambiente, apicegue pinnarum 

 ventralium nigris ; lateribus argenteo vittatim guttulatis ; pinna 

 caudali recta, apice late hyalino. 



D. i4. A. -rV, &c. 



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

 flavo ; pinnis verticalibus postice nigro tenuiter cinctis ; lateribus 

 obscurė argenteo-guttulatis. 



ChjET. Zoster. Chcet. brunneo-niger ; zona lata medid ventreque 

 argenteis s pinnd caudali recta albd : Jascia oculari nulla. 



p. ^. A. A. P. 17. C. 15. V. 1. 



The remaining species exhibited types of the genera Heniochus, 

 Cuv.; Žandus, Cuv. & Vai.; Holacanthus, Lacėp. ; and Platai, 

 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. & Vai. ' 



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. Proceedi>'gs of the Comm. of Science. 



