ii BRITISH STROMATOPOROIDS. 



of the opprobria of palaeontology. It is true that excellent work has been done in 

 reducing this chaotic group to something like order by von Rosen, Roemer, 

 Steinmann, Bargatzky, Carter, and others, but most of this work has been neces- 

 sarily fragmentary. That, in any case, much yet remains to be done is sufficiently 

 evidenced by the fact that there are hardly any species of Stromatoporoids which 

 are at this moment so clearly defined by illustration and description that their 

 claims to specific distinctness would be at once and unhesitatingly admitted by 

 palaeontologists. Indeed, there are not wanting those who hold that, in spite of 

 all apparent differences, the great majority of the described types of Stromato- 

 poroids may be perhaps only variations of one or two forms, and therefore not 

 entitled to specific distinction at all. 



My own researches have led me to think that when sufficient material is available 

 the distinctions between the different genera and species of the Stromatoporoids 

 are just as well marked and just as readily recognisable as they are in the case of 

 any other group of fossils in which the method of investigation by means of thin 

 sections is likewise absolutely indispensable. 



The present Monograph is based mainly upon my own collection of Stroma- 

 toporoids, embracing a very large series of examples which I have obtained from 

 the Silurian and Devonian Rocks of Britain, as well as a series from the corre- 

 sponding formations of North America, and a very extensive series from the 

 Devonian strata of Germany. I have likewise recently visited Esthonia, and 

 have made large collections of Stromatoporoids from the Silurian Rocks of that 

 interesting region. I may also be permitted to add that in carrying out this 

 investigation, as far as it has already gone, I have had occasion to personally 

 prepare considerably over one thousand thin sections of Stromatoporoids, the 

 labour involved in this being one which will be appreciated by all who have 

 engaged in similar work. 



Though my own collection has supplied most of the material with which I have 

 worked, I am nevertheless very deeply indebted to many of my fellow-workers for 

 the most cordial aid in the way of specimens or otherwise. I would more par- 

 ticularly express my gratitude to Mr. Champernowne, not only for the most 

 generous assistance in the way of specimens from the Devonian Rocks of Devon- 

 shire, but also for much most valuable and suggestive advice. I owe a similar 

 debt of gratitude to my friend, Dr. George J. Hinde. I am also under the greatest 

 obligations to Mr. William Madeley and Mr. J. F. Whiteaves, both of whom have 

 supplied me with material which would have been otherwise inaccessible to me, 

 and the want of which would have rendered this work seriously imperfect. I have 

 likewise received the most ungrudging help from Professor Sckluter, Dr. August 

 Bargatzky — whose recent death will be deplored by all interested in the Stroma- 

 toporoids, Professor Ferd. Roemer, Monsieur E. Dupont, Professor J. W. Spencer, 



