268 Dr. H. A. Nicholson and Mr. R. Etheridge, Jun., on 



1 Monograph of the British Fossil Corals ' * ; whilst in their 

 more extended work ' Polypiers Fossiles &c.' they placed 

 the whole of the Australian species described by Lonsdale 

 doubtfully in the genus Chcetetes f, and noticed the presence 

 of tabulae in S. crinita. 



It has already been pointed out by one of us \ that " they 

 (i. e. Edwards and Haime) thus do not notice the characters 

 relied upon by Lonsdale and M'Coy as separating Stenopora 

 and Chcetetes, whilst they introduce a feature not mentioned by 

 either of these observers. In other words, they break up Lons- 

 dale's genus into two portions, one of which, typified by Steno- 

 pora spinigera, Lonsd., they retain under Stenopora ; whilst 

 the other, comprising all the (so called) species enumerated by 

 M'Coy, King, Geinitz, and Howse, they place under Chcetetes 

 and Favosites." 



In 1851 Prof. M'Coy gave a diagnosis of Stenopora derived 

 from the study of so-called British species. He described the 

 presence of lateral gemmation, the absence of connecting 

 tubuli or foramina in the tubes, and the presence of " imper- 

 fect diaphragms perforated in the middle" §. 



This would have been a real advance in our knowledge of 

 Stenopora, because Lonsdale said no trace of transverse dia- 

 phragms had been noticed ||, were there any evidence to show 

 that McCoy's definition was based upon corals really belonging 

 to this genus H, or possessing a structure at all similar to that 

 exhibited by either of the typical forms, S. tasmaw'ensis or 

 S. ovata. M/Coy's " Stenopor-a fibrosa, Goldf.," which is the 

 first species described after his definition, is a Silurian form, 

 and is almost certainly a Monticulipora. Any appear- 

 ance of " perforated diaphragms " in Stenopora can only be 

 due to the periodic contractions of the visceral chamber 

 by the annular thickenings of the walls of the corallites, 

 the true tabula? being thin, horizontal, and complete, as we 

 shall show hereafter. 



* 1850, p. Ixi. t 1851, pp. 273, 274. 



\ Quart. Journ. Geol. Soc. xxx. p. 499. 



§ Brit. Pal. Foss. fasc. i. p. 24. 



|| Darwin's Geol. Observations, p. 162. 



% We have carefully examined specimens and thin sections of Monti- 

 culipvra [Chcetetes) tumida, Phill., which M'Coy described as a Stenopora ; 

 and we find this form to very closely approach the type species of Steno- 

 pora in internal structure, with which, in fact, it agrees in most features 

 of importance. The thickening of the tubes towards their mouths, how- 

 ever, appears to be not so distinctly a periodical and annular thickening, 

 and mural pores have not been yet detected, while several Silurian Mon- 

 ticuliporce exhibit similar features in a less marked form. Under these 

 circumstances, therefore, we have not felt ourselves justified in actually 

 removing Monticulipora {Chcetetes) tumida, Phill., to Stenopora. 



