GENERA OF FAVOSITID^E. 91 



in external appearance : while its calices are more conspic- 

 uously annular, and more obviously of two sizes, its tabulae 

 are more numerous (as compared with typical examples of 

 the former), and its mural pores are markedly smaller and 

 apparently more numerous. 



Formation and Locality. Common in the Wenlock Lime- 

 stone of Benthall Edge, and Dormington Quarry, near Stoke- 

 Edith. (Milne - Edwards and Haime and Lindstrom quote 

 it from a corresponding horizon in Gotland. It is also very 

 probable that some of the so-called Cladoporce of the Niag- 

 ara and Lower Helderberg groups of North America really 

 belong to this species ; but there are at present no means of 

 verifying this conjecture.) 



Pachypora Fischeri, Billings. 

 (Fig. 16.) 



Alveolites Fischeri, Billings, Canad. Journ., new ser., vol. v. p. 256, fig. 6, 



1860. 

 Fischeri, Nicholson, Report on the Palaeontology of Ontario, 1874, 



P- 57- 

 Cladopora Fischeri, Rominger, Foss. Cor. of Michigan, p. 47., PI. XIX., figs. 



i and 4, 1876. 



Pachypora Fischeri, Nicholson and R. Etheridge, jun., Journ. Linn. Soc., vol. 

 xiii. p. 362, PI. XX., figs. 18-20, 1877. 



Spec. Char, Corallum forming flattened expansions or 

 fronds, of a palmate form, and from one to four lines in 

 thickness, and often of considerable size. Corallites disposed 

 obliquely to the surfaces, diverging in opposite directions from 

 a central plane, and opening by distinct calices over the whole 

 free surface of the corallum on both sides of the frond. 

 The corallites are subpolygonal in shape, but their interior 

 is thickened by a secondary deposit of sclerenchyma, arranged 

 in concentric laminae, so as to leave only a comparatively small 

 oval or circular central tube. Calices sometimes rounded or 

 oval, sometimes markedly oblique and subtriangular both 

 conditions sometimes prevailing in different parts of the same 

 specimen. About three, or sometimes four, calices in the 



