BRITISH UPPEE-SILUEIAN FENESTELLII)^. 247 



differences between these fenestrate forms, thanks to the labours of 

 Prof. M'Coy, are now much better understood ; the fact that this form 

 has the pore-face on the inner side of the polyzoarium is not suffi- 

 cient to ally it with Retepora. I cannot say more about this species 

 than that it is a true Fenestella. I have seen three specimens ; and 

 in each case the pores were not visible. This recovered species will 

 not increase the number on the list, since there is good reason to 

 believe, from the thickened nature alike of interstice and dissepiment, 

 that it is only the aged condition of one of the existing species. 



GoPvGoxiA AssiMiLis, Lousd., MuTch Sil. Syst. p. 680, pi. 15, fig. 27. 

 This is a polyzoon of large dimensions. Lonsdale remarks of it 

 that " it is impossible to determine if the fossil be a true Gorgonia ; 

 but, from its great resemblance to the axis of some existing species, 

 I have ventured to place it in that genus " *. Prof. M'Coy regarded 

 it as a true Gorgonia t, and mentions the occurrence among 

 the Carboniferous fossils of some specimens referable to this 

 " obscure species " as he calls it. Lonsdale's drawing of this species 

 shows a fragment of the base. The branches are said to anastomose — 

 a feature pertaining to Retepora, but not to Fenestella, whose branches 

 are united by dissepiments. If the drawings and description are to 

 be received as exact, then there can be no doubt of its being a Rete- 

 jjora. At the same time, I think that Lonsdale intended to describe 

 a large form of Fenestella which is common in the Dudley Limestone, 

 while from some defect he gave it characters which would assign it 

 to another genus. One thing is clear, whether Lonsdale's species be 

 a Retepora or Fenestella, it has not as yet been described in either 

 genus. To avoid the difficulty which might arise if a true Retepora 

 assimilis should be found, it will be well to describe it under the 

 name of Fenestella reteporata, for reasons which I shall allude to 

 later on. In ' Siluria' it is stated that Gorgonia assimilis is Fenes- 

 tella assimilis J. Xo description is added ; and the drawing is that 

 of the fenestrules only, thus practically leaving the form unde- 

 scribed. 



Pexestella pattjla, M'Coy, Brit. Pal. Foss. pi. i. C. fig. 20. 



I have examined the type specimen in the "Woodwardian Museum, 

 and find that it is only the young frond of one of the described forms, 

 so far as I can ascertain. The cells are not so visible as they are 

 made to appear in the drawing. There is no good reason for re- 

 garding it as a separate species. Its retention, therefore, on the list 

 of Silurian species is unnecessary. Its case is analogous to that of 

 Fenestella frutex, M'Coy, which is an early stage of Fenestella, 

 plebeia^ M'Coy. 



Fenestella eegtjlaeis, Portl. Geol. Londonderry, p. 324, pi. 22, 

 fig. 3. 

 This species Portlock described and figured from the Silurian 



* Murch. Sil. Sjst. p. 680. t McCoy's Carb. Foss. Ireland, p. 196. 



\ Murchison's * Siluria,' p. 216, 216. 



