26 DEVONIAN FAUNA. 



head and tail. From P. granulosus 1 , which Goldfuss figures with the last mentioned 

 form, it differs in having no cheek-spine and in bearing tuberculations on the cheeks 

 and tail. Burmeister 2 also describes and figures P. Isevigatus, which he identifies 

 with P. Guvieri, Stein. (' Mem. Soc. Geol. Fr.,' vol. 1, p. 355, pi. xxi, fig. 6). In this 

 he gives distinct points of difference from our species, e. g. the glabella does not 

 reach the border, and the eye is further forward, and has an excavation behind it. 

 He remarks that in that species the granulations are obsolete. Sandberger, 3 how- 

 ever, seems to regard P. Isevigatus and P. granulosus as one species, remarking that 

 he has found examples of each shape both nodulated and smooth, and that at all 

 events the cheeks are smooth in both. Certainly one or two of our English species 

 have the more elongated glabella of P. granulosus, but on the supposition (of 

 which I think there is little doubt) that the enumerated specimens all belong to the 

 same form, the tuberculated cheek, neck-lobe, and pygidium, and the rounded 

 margins of the cheek sufficiently define it. Romer 4 gives a figure of P. Cuvieri, 

 which he identifies as P. Isevigatus, which is decidedly distinct from ours. 



From P. cornutus (Goldf.), which is also described by Sandberger, 5 it differs in 

 having no perpendicular area between the glabella and the border, and no cheek- 

 spines ; from P. Bohemicus, Barr, 6 the only Bohemian species resembling it, in 

 being more tumid, having larger and fewer granules, and in the shape of the 

 pygidium ; from P. Barrandei, 7 F. A. Rom., and P. orbicularis, 9 F. A. Rom., in 

 being without elongated spines. P. crassimargo, F. A. Rom., 9 approaches it very 

 nearly, and there is a possibility of its being identical; but, as far as can be 

 judged from his description, the glabella does not reach so far forward, the cheeks 

 are wider, the tail plainer, and the granulations much finer. In P. Guerangeri, 

 (Ehlert and Davoust, 10 the head is very much longer and flatter. In P. Richteri, 

 Kayser, 11 the pygidium is more largely granulated. Some of the fossils figured 

 by Phillips 12 as Calymene granulata appear to belong to this species. Although 

 granulated like the tail of Ph. Schlotheimi, Bronn, the Lummaton tails clearly 

 belong to the genus Proetus, and in their convexity agree with the heads of the 

 present species. 



1 1843, " Oerastos granulosus" Goldf., • Neues Jahrb.,' p. 557, pi. iv, figs. 4 a, b, c. 



2 1846, " P. Cuvieri," Burm., ' Org. Trilob.,' Eay Soc, p. 99, pi. iii, figs. 1, 2. 



3 1850, Sandb., ' Verst. Ehein. Nass.,' p. 30, pi. iii, fig. 2 (Trigonaspis). 



4 1876, F. Eom. ' Leth. Pal.,' pi. xxxi, fig. 3. 



5 1850, Sandb., ' Verst. Ehein. Nass.,' p. 31, pi. iii, fig. 3 (Trigonaspis ?) . 



6 1852, Barr., ' Syst. Sil.,' vol. i, p. 452, pi. xvi, figs. 1—15. 



7 1850, F. A. Eotn., ' Beitr.,' pt. 1, p. 20, pi. iii, fig. 33. 



8 Ibid., p. 20, pi. iii, fig. 34. 



9 ibid., p. 65, pi. x, fig. 9. 



10 1879, CEhl. et Dav., ' Bull. Soc. Geol. Fr.,' ser. 3, vol. vii, p. 702, pi. xiii, fig. 1. 



11 1878, Kayser, ' Abhand. der Geol. Specialk. Preuss.,' Band 2, pt. 4, p. 14, pi. i, fig. 5. 



12 J 841, Phil., «Pal. Foss.,' pi. Ivi, fig. 248, m and o only. 



