ON THE GENUS ALVEOLITES ETC. 365 



they may not be simply a variety of A. septosawe are not prepared 

 to say ; but we think little doubt can be entertained as to their 

 substantial identity with the Chcetetes radians of Eischer, a coral 

 originally described fromEussian specimens (' Oryct. de Moscou,' 

 p. 160, pi. 33. fig. 3), but which is also quoted by Milne-Edwards 

 and Haime from the Carboniferous Limestone of Kendal — on 

 precisely the same horizon as some of our own specimens. We 

 have unfortunately been unable to examine any authentic Eussian 

 examples of Gha^tetes radians ; but our specimens agree so perfectly 

 and in such minute particulars with those described and figured 

 by Lonsdale (' Euss. and Ural,' Appendix, vol. i. p. 595, pi. A_ 

 fig. 9), that we are unable to hesitate as to their identity. 



Lastly, in Alveolites depressa, Plem., we have a third coral which 

 is obviously referable to the same group as the preceding two 

 forms. The specimens which we possess of this species are large 

 massive examples, agreeing in all essential points with the de- 

 scription given by Milne-Edwards and Haime, except that we can- 

 not say that we have satisfactorily determined the presence of 

 vertical ridges in the interior of any of the corallites. These, 

 however, are both described and figured by the authors just men- 

 tioned. The species difiers almost solely in the minute size of 

 its tubes from the two preceding, the corallites being from eight 

 to ten in the space of a line. The corallites are erect ; the calices 

 are subhexagonal and not oblique ; the tabulae are complete, 

 remote, singularly regular, and often placed on the same level ; no 

 mural pores can be detected ; and a rough fracture (as in the case 

 of the two previously mentioned forms) exposes the interior of the 

 corallites. 



"We have, then, arrived at the conviction that Alveolites septosa^ 

 Elem., Chcetetes radians, Eischer, and Alveolites depressa, Elem., 

 form a very natural group of corals, which chiefly differ from one 

 another in the very trivial character that the corallites are of dif- 

 ferent dimensions. It still remains, however, for consideration to 

 what generic group these forms can be properly referred ; and on 

 this , question we have the following observations to make, the 

 only points requiring special discussion being the presence or 

 absence of mural pores, the nature of the so-called " septal tooth," 

 and the relations of the corallites to one another. 



As regards the first of these points, our specimens have only 

 yielded the negative result that we have been unable to detect any 

 signs of mural pores. In this particular instance, however, we 



