INTRODUCTION. 



Eoforo proceed iug to the subject of the present memoir some explana- 

 tion is necessary with reference to that part of it which treats of the 

 Monticuliporida). The species referred to are in the Museum of the 

 Canadian Geological and Natural History Survey, and include a fine collec- 

 tion from the vicinity of Ottawa presented by Mr. Walter E. Billings. 

 Much material yet remains to bo investigated, and there are some 

 species new to science which require further study before their generic 

 relations can be clearly defined. 



The author has followed Mr. E. O. Ulrich's classification and termi- 

 nology of the Monticuliporida), contained in his papers contributed to the 

 Journal of the Cincinnati Society of Natural History. 



A list is hero given of all the genera of the Monticuliporida) at present 

 known, descriptions of which are to be found in Mr. Ulrich's papers just 

 referred to. . . : 



Family Monticuliporida, Nicholson. 



MoniicuUpora^ D'Orbigny, (restricted). 



Sub-genus Trematopora, Hall. 



Peronopora, Nicholson. 



Ilomotrypa, Ulrich. 



Prasoporaj Nicholson and Etheridge. 



JDiplotrypa, Nicholson. 



Monotrypa, Nicholson. 



Monotrypella^ Ulrich. 



Amplexopora, Ulrich. 



Stenopora^ Lonsdale. 



Batostoma-y Ulrich. 



