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. Plyd. (dims; genis, collo in 

 fronte, pectore, tectricibiis alarum inferioribus, abdomineque 

 medio roseo-iinctin ,- cristce elongatce occipitalis plumisbasi roseis, 

 apice albis, macula Jlava in mtdio iiotatis; pogoriiis remigiim 

 rectricumque internis roseis, illorum satiiratioribus. 

 Statura Plyct. sidphurei, Vieill. 



Eleven species of ChcBtodons, 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 Chatodon as 

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

 more particularly the Chat, strigaugulus, Sol.; the Chat, vittatiis, 

 Schn,; the Chat. Lunula, Cuv. c4 Val.; and two species which he 

 believed to be nefv to science, and which may be thus characterized j 



Ch;et. flavescens. Chcet. Jlavus ; ore, fascia ocidari, linea 

 pinnas dorsalem analemque postice ambiente, apiceque pinnanm 

 ventralium nigris ; lateribus argenteo vittatim guttulatis ; pinna 

 caudali recta, apice late hyalino. 



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



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

 flavo; pinnis verticalibus postice nigro tenuiter cinctis ; lateribus 

 obscure argenteo-guttulatis. 



Ch^t. Zoster. Chat, brunneo-niger ; zona lata media ventreque 

 argenteis ; pinna caudali recta alb d: fascia ocidari nulla. 



D. If. A. A. P. 17. C. 15. V. 1. 



The remaining species exhibited types of the genera Heniochus, 

 Cuv.; Zanclus, Cuv. Sc 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 

 Fro^. 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. 



