PHACOPS. 5 



easily distinguished by its more regular and overhanging glabella, finer granules, 

 and smoother cheeks, and from G. Schlotheimi by its less elevated eyes, shorter 

 glabella, and the narrower axis of its tail. 



It comes strikingly near to Phacops fecundus, Barr., 1 and especially to some 

 of its varieties from Bohemia. It may, however, be distinguished from them by 

 the more pointed, flatter, and overhanging frontal lobe, the smooth cheek, and the 

 different position of the eye, which in the Bohemian species has usually a con- 

 siderable expanse of cheek behind it. It agrees with Ph. latifrons as against 

 Ph. fecundus in having eighteen and not nineteen perpendicular rows of lenses, 

 and with Ph. fecundus as against Ph. latifrons in the eye not reaching the highest 

 level of the glabella. Ph. fecundus, on the other hand, differs from Ph. granulatus 

 in the much greater number of rows of facets in the eye. 



Dr. Kayser 2 describes a German variety of Ph. fecundus, and points out several 

 distinctions between it and Ph. latifrons, which still further show that Ph. batra- 

 cheus is not to be ranked with either. He also proves that the fossil described by 

 F. A. Eomer 3 as Ph. granulatus belongs really to Ph. fecundus. 



In a paper on the zoology of Gabrieres (Languedoc) Dr. F. Freeh* describes 

 " Ph. fecundus mut. nov. supra- devonica," and this seems to come still nearer to 

 Ph. batracheus. Apparently, however, it differs from it in the cheeks being finely 

 granulated, the cheek-groove deep, the neck- and basal lobes narrower, the glabella 

 more rounded in front, and the cheeks narrower near the posterior angle. The 

 head would seem to be rather longer, and the furrows of the glabella less distinct. 



No other G-erman or Bohemian species resembles it. In Ph. signa.tus, Corda, 5 

 the eye is much more forward ; in Ph. trapeziceps, Barr., 6 the neck is much wider, 

 and the glabella slopes to the front border; in Ph. livening hausi, Barr., 7 the head is 

 more elongate and the eye more forward. In Ph. cephalotes, Barr., 8 the glabella is 

 much larger and more protuberant ; and in Ph. Boechi, Corda, 9 the basal lobe is 

 linear and the glabella more rounded. 



Ph. breviceps (?), Barr., is described by Barrois 10 from a pygidium, which seems 

 wider than that of our species, and this distinction is fully borne out by Barrande's 

 own description of that species. ;i 



1 1852, Barrande, ' Syst. Si].,' vol. i, p. 514, pi. xxi, figs. 1 — 27 ; pi. xxii, figs. 32, 33 ; and Supple- 

 ment, pi. xiii, figs. 1 — 14. 



2 1878, ' Abhandlungen zur geol. Specialkarte von Preuss.,' Band 2, pt. 4, p. 19, pi. ii, figs. 1 — 12. 



3 I860, F. A. Eomer, ' Beitr.,' pt. 5, p. 8, pi. 34, fig. 7. 



4 1887, Freeh, 'Zeitsch. deutsch. geol. (resell. ,' p. 469. 



5 1852, Barr., ' Syst. Sil.,' vol. i, p. 521, pi. xxiii, figs. 1—4, Etage F. 



6 Ibid., vol. i, p. 526, pi. xxii, figs. 19—23, Etage E. 



7 Ibid., vol. i, p. 522, pi. xxi, figs. 28—31, Et. G. 8 Ibid., vol. i, p. 509, pi. xx, figs. 1—14, Et. G. 



9 Ibid., vol. i, p. 513, pi. xx, figs. 30—32, Etages F and G. 



10 1886, Barrois, ' Ann. Soc. Geol. du Nord,' vol. xiii, p. 137, pi. ii, fig. 4. 

 ii 1852, Barrande, ' Syst. Sil.,' vol. i, p. 518, pi. xxii, figs. 24—31, Et. F. 



