PREFACE. 



The present work has no claim to be called a " Monograph," 

 since it does not even exhaust my own collection of Mon- 

 ticuliporoids, upon which it is entirely based; while a large 

 amount of additional material, much of it new and important, 

 is contained in the cabinets of others or in public museums. 

 Moreover, the group of the Monticuliporoids, from the diffi- 

 culties attending its study, has always been more or less 

 neglected by palaeontologists ; and we may be quite sure that 

 there exist many new and interesting types which yet remain 

 to be discovered. The time, in fact, for writing a " Mono- 

 graph " of the Monticuliporidse has not yet arrived ; and the 

 present work is simply an attempt to ascertain and clearly 

 record the structure of a number of well-marked species of 

 Monticulipora, with special reference to the microscopic and 

 really fundamental characters of these. Palaeontologists, indeed, 

 have now universally recognised that, in such difficult forms 

 as the Monticuliporoids, the microscopic structure is the chief 

 element in the determination of species ; since surface-char- 

 acters may not be recognisable, or may vary greatly according 

 to the state of preservation of the specimens, or other similar 

 circumstances, while mere external form is a most treacherous 



