232 BRITISH STROMATOPOROIDS. 



Western Australia of two European Stromatoporoids, viz. Actinostroma dathratum, 

 Nich., and Stromatoporella eifeliensis, Nick. ("Notes on the Palaeontology of 

 Western Australia," ' Geol. Mag.,' dec. 3, vol. vii, p. 193, pi. viii). 



In 1891 appeared the third part of the present Monograph. The species 

 described in this for the first time are Labechia scabiosa, L. stylophora, Stroma- 

 topora Garteri, 8. inssgualis, and 8. florigera. 



Lastly, in 1891 was published part iv of the memoir by the present writer, 

 " On some New or imperfectly Known Stromatoporoids " (' Ann. and Mag. Nat. 

 Hist.,' ser. 6, vol. vii, pp. 309 — 328, pis. viii — x, and two engravings). The 

 forms described are principally American, and include the following : — Stroma- 

 topora antiqua, Nich. and Mur. ; 8. (Gaunopora) Hudsonica, Daws. ; 8. Garteri, 

 Nich. ; S. borealis, Nich. ; Adinostroma expansum, Hall and Whitf . sp. ; A. Tyrrellii, 

 Nich. ; A. Whiteavesii, Nich. ; A. matutinum, Nich. ; A. fenestratum, Nich. ; Syringo- 

 stroma ristigouchense, Spencer sp. ; S. (Stromatopora) nodulakim, Nich: ; and 

 S. densum, Nich. The species described for the first time are Stromatopora 

 borealis, Adinostroma Tyrrellii, A. Whiteavesii, and A. matutinum. It is further 

 pointed out that the form described by the author from the Hamilton formation 

 of Ontario under the name of Stromatopora nulliporoides (' Report on the 

 Palaeontology of Ontario,' 1875, p. 78) is identical with the previously described 

 Goznostroma inerustans of Hall and Whitfield from the Devonian rocks of Iowa, 

 and that the latter is properly referable to the genus Stromatoporella. 



APPENDIX. 



By the kindness of Professor Edward Orton, of the State University of Ohio, 

 I have been permitted to re-examine the fossil which I originally described as a 

 Stromatoporoid under the name of Didyostroma, undvlatum, and which I regarded 

 as the type of the genus Didyostroma (' Palaeontology of Ohio,' vol. ii, p. 254, 

 pi. xxiv, fig. 6, 1875). In the Introduction to the present work (p. 85) I pointed 

 out that the genus Didyostroma, for want of knowledge of its microscopic 

 structure, could not be regarded as being " adequately defined or satisfactorily 

 established." Having now made a careful examination of the original example of 

 Didyostroma undulatum, Nich., by means of thin sections, I am able to state that 

 the fossil so named is certainly not referable to the Stromatoporoids. Its precise 

 affinities are not absolutely clear, but it is sufficient for my present purpose to 

 }:)oint out that the genus Didyostroma, Nich., must no longer be regarded as a 

 member of the great series of the Stromatoporoid ea. 



