64 CARBONIFEROUS CEPHALOPODA OF IRELAND. 



It is also distinguished by having closer septa and less distinctly marked sulci 

 than those in Sowerby's species. 



It may not be superfluous to mention finally that I had not seen the 1862 issue 

 of M'Coy's work when writing the 'Catalogue of the Fossil Cephalopoda' in the 

 British Museum, no copy of it being contained in the library of that institution, 

 and therefore, like de Koninck, I was then unaware of the existence of the " note " 

 quoted above. 



I have next to refer to Professor Hyatt's distribution of the group of forms 

 to which the present species belongs. His observations upon them are very brief. 

 Referring to Strohoceras sulcatum, J. de C. Sowerby, sp., he says, " This has 

 smooth sides, is more compresed, and differs from the Naut. suJeatus of de Koninck, 

 * Calc. Carb.,' p. 27, for which I propose the name S. helgicAimy The following 

 European species are also referred to tStrobocei-as by Hyatt, S. (Naut.) hisuJcahnn, 

 sp., de Koninck ; PhiUipsiamtm, sp., d'Orb., as figured by de Koninck ; Edivardsia- 

 ?ium, sp., de Koninck; cordiostomum, sp., de Koninck, and also S. (Naut.) gerrnanuvi, 

 Phillips, sp., as figured by d'Orbigny in the ' Paleontologie universale,' pi. Ixxxv. 



I cannot understand upon what ground Professor Hyatt rests his statement 

 that Strohoceras sulcatum has smooth sides; they are, on the contrary, beset with 

 ridges and furrows, the more prominent of the former being quite conspicuous 

 upon casts, even the lesser ridges not becoming obsolete till the body-chamber is 

 reached. 



Professor Hyatt does not indicate in detail the characters which separate 

 8. sulcafiLm,J. de C. Sow., sp., from *S^. heJ(jicum, A. Hyatt { = N. siiJcatvs, de Kon., 

 noit Sow.). The most obvious of them consist, firstly, in the relative dimensions 

 of the whorl, which have already been tabulated ; secondly, in the much larger size 

 of the central vacuity in 8. hehjicum, conspicuous in one of de Koninck's figures 

 ('Calc, Carb.,' pi. xxvii, fig. 2, selected by Hyatt as typical). 



Localities. — Little Island, near Cork; Mullaghfarry and Crosspatrick, Killala, 

 county of Mayo ; Carnteel, county of Tyrone. 



h. Stkobocekas ceassum, sp. nov. Plate XX, figs. 13 a, &, c. 



Description. — The only specimen is a worn fragment of a portion of the body- 

 chamber of a thick discoid shell, most of the test of which remains. It is sub- 

 triangular or broadly sagittal in section, abruptly truncated above, expanding 

 rapidly to the margin of the umbilicus below. The periphery is narrow, but much 

 wider than in related species (cf. 8: stdcatum', J. de C. Sowerby sp., p. 59) ; it 

 is very slightly, almost imperceptibly concave, and is bounded on each side by 

 distinct marginal keels. The edge of the umbilicus is bordered by a keel, a 



