] 52 • Geological Society : — 



white ; if they return with their proportions altered, the pad is 

 acoustically coloured. 



In these experiments my assistant, Mr. Cottrell, has rendered 

 me material assistance. 



GEOLOGICAL SOCIETY. 

 [Continued from vol. xlix. p. 481.] 



June 24, 1874. — John Evans, Esq., E.R.S., President, 

 In the Chair. 



The following communications were read : — 



8. " Description of species of Ghcetetes from the Lower Silurian 

 Rocks of North America." By Prof. H. Alleyne Nicholson, M.D., 

 D.Sc, E.R.S.E., E.G.S. 



In this paper the author accepted the union of Ghcetetes and 

 Stenopora made by Milne-Edwards and Haime, and stated that 

 Monticulipora, D'Orb., and Nebulipora, M c Coy, also seemed to him 

 to belong to the same generic group, for which he proposed to 

 employ the name Chcetetes. The genus thus denned he proposed to 

 divide into 4 groups, under which he described the following North- 

 American species : — 



Group I. Ramose species. 

 G. Dalei, rugosus, pulchellus, and Fletcheri (M.-Edw. & Haime) ; 

 C. gracilis (James) ; and G. approximatus, attritus, delicatulus, no- 

 didosus, Jamesi, and rhombicus, sp. nov. 



Group II. Erondescent and Palmate species. 

 C. mamrnulatus (M.-Edw. & Haime), frondosus (D'Orb. ?), and 

 clathratulus (James). 



Group III. Massive and Discoid species. 

 G. petropolitanus (Pand.) and discoideus (James) ; and 



Group IY. Incrusting species. 

 G. papillatus (M c Coy), and corticans and Ortoni, sp. nov. 

 Most of the species are from the Cincinnati group near Cin- 

 cinnati. 



9. "On the composition and structure of the Bony Palate of 

 Gtenodns." By L. C. Miall, Esq. Communicated by Prof. P. Martin 

 Duncan, E.R.S., E.G.S. 



The specimen noticed by the author was obtained from the Low- 

 Main Coal-seam of Newsham, Northumberland. The component 

 bones are a parasphenoid and a pair of pterygo-palatals. The left 

 dental plate agrees with the type of Gtenodus cristatus (Agassiz) in 

 the Leeds Museum. The author describes the bones and teeth in 

 detail. He regards Gtenodus as closely related to Ceratodus in the 

 structure of the palate, and as differing but little from the Devonian 

 Dipteriis. 



