G4 DEVONIAN FAUNA. 



variable, and most probably the slight differences mentioned above are due to the 

 Wolborough specimens being younger shells. It will be seen on reference to the 

 figures that the Wolborough specimens themselves show considerable variation. 

 G. costidatus, d'Arch. et de Vern., appears to agree with the Wolborough specimens 

 exactly, except that it is circular instead of being (as are two out of the three) 

 elliptic, and that the sides are perhaps a little shorter ; and there is no reason 

 to question its identity with them. With Phillips's types, however, its agreement 

 is more doubtful, though from the fact that the French authors describe the keel 

 as striated in well-preserved specimens, and that Phillips's species varies so much 

 with age it is most probable that they in common with our present fossils belong 

 to it. Again, G. Wildungensis, Waldsmidt, has so much the character of Phillips's 

 species that I believe it must be classed with it. From Mr. Vicary's fossil it 

 chiefly differs in being flatter and not elliptic ; but the Jermyn- Street specimens on 

 the whole agree with it, though the suture-line of the English shells, being 

 unknown, prevent a very positive identification. 



Affinities. — G. paiicistriatus,^ d'Arch. et de Vern., has much fewer and more 

 direct striations. 



G. costatus, d'Arch. et de Vern.,^ has much wider ribs. Sandberger^ unites 

 G. tuherculosus and G. costatus of d'Archiac and de Vern., calling the resultant 

 species G. tuherculoso-costatns , d'Arch. et de Vern. ; and in the shell which he thus 

 figures the costse are fewer and straighter, and the whorls more numerous than 

 in ours. Tietze* agrees with Sandberger in this view, and gives a very similar 

 figure, with ribs much straighter than in the species under consideration. Lastly, 

 G. anguliferus, F. A. Romer/ has shorter whorls, and its costse are fewer and as 

 strong upon the back as upon the sides. 



5. GoNiATiTES MOLARius, n. sp. PI. V, figs. 11, 11 a ; PI. VI, figs. 4, 4 a, 6, 6 a. 



1841. GrONiATiTES EXCAVATus, Phil. Pal. Foss., p. 121, pi. 1, fig. 232 (not Phillips, 



Geol. Torks.). 

 1850. — DISCUS ?, i^. ^. Bomer. Beitr., pt. 1, p. 39, pi. vi, figs. 7 a, 



b, c (juv.). 

 1888. — EXCAVATUS, Etheridge. Foss. Brit., vol. i, Pal., p. 167, 



' 1842, d'Arch. and de Vern., ' Geol. Trans.,' ser. 2, vol. ii, pt. 2, p. 389, pi. xxv, figs. 8 a, h. 



2 Ibid., p. 340, pi. xxxi, figs. 1, la. 



^ 1851, Sandberger, ' Verst. Ehein. Nassau,' p. 64, pi. iv, fig. 1 ; pi. viii, fig. 2. 



* 1870, Tietze, ' Dev. Schicht. Ebersdorf.,' p. 28, pi. i, fig. 6. 



■' 1850, F. A. Eomer, 'Beitr.,' pt. 1, p. 40, pi. vi, figs. 12a, h, c. 



