50 CARBONIFEROUS CEPHALOPODA OF IRELAND. 



produce a cancellated pattern of ornament comparable with that of the recent 

 Naufilu>t in the same stage of growth, and of other coiled extinct Nautiloid shells 

 {Discitoceras, e. g.) which lose this ornamentation in the adult shell. The trans- 

 verse lines become obsolete before the end of the first whorl, but the longitudinal 

 lines die out at about the first quarter of the second whorl, among the last to 

 disappear being two lines just below the tubercles. Transverse lines of growth 

 of a sigmoid form (much drawn out) are seen when the test is well preserved. 



Affinities. — M'Coy (' British Palaeozoic Fossils,' p. 588) remarks that the 

 present species is distinguished completely from N. tuberculatus '^ by the great 

 thickness or width of the mouth as compared with the diameter, the much more 

 rapidly enlarging Avhorls, much deeper and narrower umbilicus, direction of the 

 flattening of the tubercles, acutely elliptical form of the transverse section of the 

 whorls, and forward instead of backward wave of the edge of the septa at the 

 middle of the periphery. The accuracy of this summary of the divergent 

 characters of the present species when compared with Temn. tuberculatus is 

 established by an examination of the type specimen of the latter in the British 

 Museum. 



De Koninck, in describing the present species from Vise, Belgium, compares 

 it with N. biaugulatus, J. de C. Sowerby {? Gaelonautilus cariniferus, J. de C. 

 Sowerby, sp.), and with Nautilus triherculatus, J. Sowerby, and Nmitiln^ latns, 

 Meek and Worthen. He distinguishes M'Coy's species from Sowerby's and Meek 

 and Worthen's by its smaller size, the greater relative height of its aperture, the 

 depth of its umbilicus, and the form of the septa. As far as can be judged by 

 the figures, there seems much to justify de Koninck's identification of the Vise 

 fossil with Temnocheilus coronatus ; and Mr. E. J. Garwood expressed the same 

 view, in a letter to the writer, after having seen the specimens in the Natural 

 History Museum at Brussels in 1893. 



Bemarlcs. — Until Mr. E. J. Garwood's fortunate discovery of this species in 

 the Carboniferous Limestone of Stebden Hill, near Cracoe, Yorkshire,^ it was but 

 imperfectly known. The fine series he collected has added all the necessary 

 information, though M'Coy, it is true, was enabled to somewhat amend his 

 original description of the species by means of specimens afterwards obtained in 

 the Carboniferous Limestone of Lowick, Northumberland.^ One of Mr. Garwood's 

 specimens, now in the British Museum, is figured for comparison with M'Coy's 

 type, and tc show the characters of the young shell, which are not seen in the 

 latter (PI. XVIII, figs. 1 a, 2 a). 



' J. Sowerby, ' Min. Conch.,' vol. iii, p. 90, pi. ccxlix, fig. 4. 



' ' Geol, Mag.,' dec. 4, vol. i, p. 295. 



^ These are in the Woodwardian Museum, Cambridge. 



