= Nw 
124 _ PROF, GROOM ON THE CAMBRIAN AND’ [Feb. 1902, 
Salt.,' O. Selwynii, Salt.,? and O. marginata, Crosfield & Skeat.? 
It also approaches such forms as ‘Ogygia’ producta, Hall & 
Whitfield, of the Quebec Group,* and ‘Asaphus’ Wirtht, Barr. 
(pygidium), from the Tremadoe of. Hof.’» The Bronsil form differs, 
however, from all of these in several respects. It comes nearest, 
perhaps, to ‘ Ogygia’ peltata. From this species it differs in the 
small size and imperfect segmentation of the pygidium, and in the 
axis being narrower, anih apparently prolonged farther towards 
the hinder mar gin of the pygidium. 
According to “Brogger, O. peltatais not an Ogygia, but probably 
a true Niobe ; and the same may probably be said of ‘ Ogygia’ 
Liqnieresi,’ * Ogygia’ producta,’ and Asaphus Wirthi.’ The same 
author throws doubt ou the possession of genal horns by ‘ Ogygia ’ 
peliata. ‘They are, however, shown with sufficient clearness in the 
original specimen from which Salter’s fig. 8, pl. xvi (‘ Monograph 
of British Trilobites’) is taken, and which is still preserved in the 
Museum of Practical Geology, Jermyn Street. The figure, though 
condemned by Salter himself, is sufficiently good in this respect. 
The labrum agrees even more closely with that of such forms as 
Niobe insignis, Lurs. than would appear from Salter’s figure (op. cit. 
pl. xxv*, fig. 3), or from Novak’s figure.” If, therefore, Brégger’s 
suggestion,” that the name Ptychocheilus should be applied to horned 
species of Viobe with the typical labrum of that genus, be adopted, 
Novik’s reference of ‘ Ogyqia’ peltata to Ptychocheilus would appear 
to be justified. 
NiosE Homrrayt, Salter (?). (Fig. 31, p. 125.) 
Niobe Homfrayi, Salt., is probably represented, in the Grindrod 
Collection at Oxford, by two imperfect specimens from the Bronsil 
Shales of the Southern Malverns. In one of these (fig. 31) the 
characters seen agree with those ofthis species. It is only perhaps in 
the labrum that the Malvern species may differ from WV. Homfrayi. 
This structure, though imperfectly preserved, shows much the same 
form and dimensions as those described by Salter in the latter species, 
but the anterior lobe appears to be raised up in front into an oval 
eminence, which, however, is not improbably adventitious. The 
form shown by the labrum approaches that seen in the oldest 
Scandinavian species of Niobe and Oyygia," especially that of the 
last-mentioned genus; but it appears to be a little more elongated, and 
' J. W. Salter ‘Brit. Trilob.’ Monogr. Palzont. Soc. (1864-83), pp. 1385-36, 
inne: 2 id. pp. 136-37. 
3 Quart. Journ. Geol. Soe. vol. lii (1896) y ». O38. 
* «U.S. Geol. Explor. 40th Parallel’ vol. iv (1877) p. 244 & pl. ii, figs. 31-34. 
> Neues Jahrb. 1868, p. 680. 
° Nyt Mag. for Naturvidensk. vol. xxxvi (1898) pp. 170 & 171. 
* Lbid. p. 228. 8 Lbid ee 22; 
° Beitrage zur Palewont. Oesterreich-Ungarns u. des Orients, vol. iii (1884) 
D. Dv. 
Po Nyt Mag. for Naturvidensk. vol. xxxvi (1898) p. 219. 
il Brégger, Bihang t. Kongl. Svenska Vet.-Akad. Handl. vol. xi i (1886) no. 8, 
pp. 46 et seqq. 
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