INTRODUCTORY REMARKS. 



It may be doubted if there be any small group of fossil organisms which has 

 given greater trouble to its investigators than that of the Stromatoporoids. Their 

 study is, in fact, attended with quite peculiar and special difficulties, as will become 

 abundantly evident in the course of the following Monograph. For my own part, 

 I am very willing to admit that I have been led, by a prolonged and minute study 

 of a very extensive series of these organisms, to modify or abandon various views 

 which my earlier researches had induced me to accept as more or less probable. Nor, 

 of course, do I claim anything approaching to finality for the present work, though 

 I may be allowed to hope that the results herein set forth may afford a satisfactory 

 basis for further and more extended inquiries. 



Much of the difficulty attending the investigation of this group of fossils arises 

 from the fact that so many specimens, though seemingly unaltered, have in reality 

 been so far affected by mineralisation as to exhibit structural features which are 

 only capable of proper interpretation in the light of the facts shown by other 

 comparatively unaltered examples, or which, in the absence of such examples, 

 become positively misleading. It sometimes happens, indeed, that almost all the 

 specimens from some particular region are thus structurally affected by mineralisa- 

 tion, and that their study can only be satisfactorily carried out by means of 

 examples obtained from the corresponding formation of some other region. Thus, 

 I think it may fairly be asserted that the investigation of the Stromatoporoids of 

 the Devonian Limestones of Devonshire, most of which are extensively altered by 

 crystallisation or distorted by pressure, would prove an exceedingly difficult or 

 well-nigh impossible task, except by the aid afforded by comparison with the 

 similar but less altered forms which occur in the Devonian Rocks of Germany. 

 Moreover, in the determination of these, perhaps to a greater extent than is the 

 case with any other group of fossils, progress is absolutely impossible except by an 

 unstinted application of the modern methods of microscopical inquiry — methods 

 which involve considerable labour, and to which all observers are not equally 

 willing or able to have recourse. 



For the above-mentioned reasons, amongst others, it has come to pass that the 

 Stromatoporoids have been, to a large extent and until comparatively recently, one 



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