HISTORICAL INTRODUCTION. 13 



As regards general results, the main conclusion reached by Von Rosen is that 

 the skeleton of the Stromatoporoids is composed of horny fibres arranged in bundles, 

 and that these organisms are referable to the group of the Keratose Sponges, or allied 

 to these. The minute openings on the surface of many Sti-omatoporoids he regards 

 as "pores," and the larger openings, which are occasionally present, as " oscula." In 

 this latter view, he has been preceded by D'Orbignyand others, and has been followed 

 by many later investigators. In his opinion that the skeleton of the Stromatoporoids 

 was in reality of a horny nature, Von Rosen was preceded by Eichwald ; but 

 there can be no hesitation, in the light of all known facts, in unequivocally rejecting 

 this view. In spite of the above erroneous conclusion as to the composition of 

 the skeleton of the Stromatoporoids, Von Rosen's work will continue, justly, to 

 retain its position as a classical treatise upon a most difficult group of organisms. 



In 1870, Dr. Gustav Lindstrom jmblished a valuable paper on the Anthozoa 

 perforata of Gotland (' Kongl. Svenska Vetenskaps-Akad. Handlingar,' Bd. ix), 

 in which he describes and figures the Pontes discoidea of Lonsdale as a Stromato- 

 poroid, under the name of Ccenostroma discoideum. An examination of the original 

 specimen, now preserved in the British Museum, has shown that Dr. Lindstrom is 

 perfectly correct in the belief that Porites discoidea, Lonsd., was really founded 

 upon a Stromatoporoid. I should be disposed, however, to think that in his descrip- 

 tion of this species, Dr. Lindstrom has included more of the Wenlock Stromato- 

 poroids than Lonsdale's species, and, for reasons above given, I am unable to 

 retain the genus Ccenostroma, Winch. In Lindstrom's opinion, Geeno stroma is a true 

 Coral, and is allied to the Montiporinm. On the other hand, he regards the genus 

 Stromatojpora, Goldf., as distinguished from Gaenostroma, "Winch., as having quite 

 different affinities, and as being probably related to the Foraminifera. 



In a memoir on the affinities of the Anthozoa tabulata (' CEfversigt af Kongl. 

 Vetenskaps-Akad. Forkandl.,' 1873, translated in the 'Annals of Natural History,' 

 187G), Dr. Lindstrom expresses the opinion that Ccenostroma, Winchell, presents 

 certain points of likeness to Labechia, B. and H. He further makes the very 

 important suggestion that the genus Labechia is of Hydrozoal affinities, and is 

 related to the recent genus Hydractinia. To Dr. Lindstrom, therefore, belongs, 

 so far as I am aware, the credit of having first publicly pointed out the direction 

 in which the true relationships of the Stromatoporoids might be looked for. 



In the ' Twenty-third Annual Report on the State Cabinet,' dated 1873, Prof. 

 Hall and Mr. Whitfield describe as new species five Stromatoporoids from the 

 Devonian Rocks (Chemung group) of North America. These are named Stroma. 

 topora erratica, S. expansa, S. (Gaenostroma) incrustans, 8. (Ccenostroma) solidula, 

 and Caunopora planulata. It would not appear that the last of these is really of 

 the same nature as the fossils referred properly to Caunopora, Phill, as it seemingly 

 does not possess the walled tubes which are characteristic of the latter. 



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