294 Proceedings of the Royal Irish Academy. 



Genus YIII. Ehaphoxeis, Ekr. 



The cliaracters on which, this genus is grounded arc : — First. The 

 symmetry of the frustules by which they are separated from Cocconeis, 

 which some of the species in other respects closely resemble. Secondly. 

 They do not form parallel filaments, by which circumstance they are 

 distinguished from those of Denticula and Dimeregramma. Thirdly. 

 The striae are interrupted by the intei'position of an unstriate longi- 

 tudinal band, more or less broad — a feature by which the forms of the 

 genus may be discriminated from those of Diatoma and Odontidium. 



"WTiile adopting this genus, I do so with somewhat of the feeling 

 which Grunow has so well expressed in the following remarks : — 

 " The genus Ehaphoneis, which here I represent in Ehrenberg's 

 sense of it, is widely separated therefr'om, for the purpose of receiying 

 forms which, in point of fact, have but little generic relationship to 

 each other. j\Ieanwhile, it is nevertheless a sort of refuge for various 

 Diatoms which have not been thoroughly investigated, and which, 

 in some cases, are known only so far as their side view is concerned. 

 A portion of these, upon more mature knowledge, may be transferred to 

 Dimeregramma, while others, fr'omtheii' Cocconeis-like habit, must cer- 

 tainly be constituted as a special genus. Yery numerous instances 

 of forms belonging to the latter class have come under my notice ; 

 and I am convinced that they do not underlie the upper valves of 

 Cocconeis — and for this reason, that I have never found associated with 

 them valves of Cocconeis with a central nodule, or valves which in 

 other details of structure would be supposed to correspond with them." 

 Yerhand der K. K. Zool. Bot. Gesel., Band xii., 1862, p. 378. Two 

 of the forms herein included — namely, Bhaphoneis amphiceros and 

 Bhaphoneis rhombus. Smith has placed side by side, under the same 

 generic name, with Doryphora Boeckii, with which, beyond the fact 

 of being stipitate, they have little in common. Bhaphoneis amphi- 

 ceros was observed by Xiitzing in situ, and described and figurecl by 

 him as stipitate. I am not aware whether, in the case of the other 

 foims included, a similar fact has been noticed. ^Wh.atever presump- 

 tion there may be in favoru- of the supposition, this feature cannot be 

 as yet admitted as a general characteristic of the gToup. Odontidium 

 Harrisoni, Y^m. Sm., the fr'ustules of which in general structiu'e are 

 similar to those of Denticula, as I have defijied that genus, exhibits 

 nevertheless a different habit of growth, the fr'ustules being attached 

 by a cushion or short stipes, and forming a filament, the several frus- 

 tules adhering by their ends to one another. It seems then in this 

 respect, as well as in the interrupted striation, to stand in close 

 relationship with Bhaphoneis amphiceros, and on this account I include 

 it in the same genus ; not indeed because I feel quite satisfied on this 

 point, but because, all things considered, I regard this most suitable 

 as a provisional arrangement. 



