GUELPH FAUNA IN THE STATE OF NEW YORK 2"] 



Mr Lambe, who has undertaken a revision of the Canadian corals, 

 united Diplophyllum and Eridophyllum under Diphyphyllum, which is 

 characterized as possessing no " inner wall " ; and Diplophyllum 

 caespitosum is said to have " dissepiments arching upward, between the 

 septa, against the outside wall, generally in a single series, their outer edges, 

 as seen in transverse section, assuming the appearance of an inner wall 

 situate less than i mm from the wall proper." This appears to us to con- 

 firm the presence of an inner wall in D. caespitosum, as the inner wall 

 of the other genera, where it can be said to be typically developed, such as 

 Lonsdaleia and Acervularia, consists also of a single or terminal series of 

 strongly developed upward arching dissepiments. We must, therefore, as 

 long as the term " inner wall " is used loosely, consider D. caespitosum 

 as possessing this structure. It would seem to us that the term should be 

 restricted to that inner wall which is often formed by the lateral thickening 

 of the septa, in like manner as the pseudotheca. 



From sections of Diplophyllum caespitosum, of Erido- 

 phyllum verneuilianum, the type species of that genus, and of 

 E. simcoense, given by Lambe in the paper above cited, it becomes 

 apparent that the internal wall of Eridophyllum, or walls (for in E. ver- 

 neuilianum occur two series of dissepiments) are also constructed as 

 in Diplophyllum, and that the difference between the two genera can at 

 present be based only on the different development of the septa, while the 

 difference assumed to consist in the failure of the septa to transgress beyond 

 the inner wall in Eridophyllum is not valid. To this difference may be 

 added the presence of the characteristic radiciform expansions in Erido- 

 phyllum. Diphyphyllum differs from the two latter genera by its very 

 feebly developed septa, which do not reach the internal wall, and by its 

 different geologic range. While these distinctions in the three genera may 

 be only of degree, the groups denoted by them differ also in geologic age, 

 Eridophyllum being essentially a Devonic and Diphyphyllum entirely a 



Carbonic genus. 



Diphyphyllum caespitosum occurs, according to Billings, as 



