MINUTE STETJCTURE OF STEOMATOPORA AND ITS ALLIES. 191 



Eichwald, on the other hand (' Lethaea Eossica,' vol. i. p. 3i5, 

 1860) defines Stromatopora as composed of a spongy mass con- 

 structed of closely approximated lamellae and enveloping other 

 organic bodies, its surface covered with minute rounded pores 

 arranged without order over the whole surface of the skeleton, 

 the latter being formed of a network of very minute horny fibres. 

 M. Eichwald is thus the first, so far as we are aware, to promul- 

 gate the view, afterwards so strongly supported by Yon Eoseu, 

 that the Stromatoporoids were really composed of horny fibres in 

 their original constitution. 



In 1866, Prof. Winchell (' Eeport on the Michigan Peninsula ') 

 described several species of Stromatupora ; but we have unfortu- 

 nately been unable to obtain access to this work for consul- 

 tation. 



In the ' Proceedings of the American Association ' for 1866 the 

 same author also defines the genus Coenostroma, and discusses the 

 affinities of the Stromatoporoids in general ; but this memoir also 

 we have unluckily been unable to consult. 



The most important contribution to the structure and history 

 of the Stromatoporoids is that published in 1867 by Yon Eosen, 

 under the title ' CTeber die Natur der Stromatoporen, und iiber 

 die Erhaltung der Hornfaser der Spongien im fossilen Zustande.' 

 In this work the author considers the structure of Stromato- 

 pora as elucidated by means of vertical and horizontal (or, 

 better, " tangential") sections prepared for microscopic examina- 

 tion, and the highest praise must be accorded to his plates for 

 their accuracy and fidelity to nature. We are not, however, 

 able to agree with the main thesis of his valuable memoir, which 

 he supports by evidence drawn both from the study oi Stromato- 

 pora itself and from collateral sources, namely, that the skeleton 

 of the Stromatoporoids was originally composed of minute horny 

 fibres, which were replaced, in the process of fossilization, by car- 

 bonate of lime. We quite coincide, on the other hand, with the 

 author's view, that the belief that the ordinary and typical Stro- 

 matoporoids were originally siliceous is not supported by the evi- 

 dence at present in our hands. 



In 1870, Dr. Gustav Lindstrom published an important paper 

 on the Anthozoa Perforata of Grotland (' Kongl. Svenska Ye- 

 tenskaps-Akad. Handlingar,' Bd. ix.), in which he describes and 

 figures the Porites discoidea of Lonsdale as a Stomatoporoid under 

 the name of Coenostroma discoideum. He regards Coenostroma as 



