60 DEVONIAN FAUNA. 



which they have now become nearly parallel. Suture-line and siphuncle unknown. 

 Chambers very narrow and concave. 



Size. — 34 mm. high, 25 mm. wide, 12 mm. deep. 



Locality. — A single perfect specimen from Lummaton is in my collection; 

 and the polished section of about a whorl of a rather larger specimen which wants 

 the surface, but shows the shape of the chambers, is in the Torquay Museum. 



Bemarhs. — Though only two specimens of this beautiful fossil are known to 

 me, one is so well preserved that the characters of the species may be considered 

 fairly well known. It forms a link between G. ohliquus and G. transitorius, 

 presenting considerable difference from either form It is unfortunate, as the 

 suture-lines of both these forms can be traced, that those of the present fossil 

 cannot be seen. It may, however, be distinguished by the highly ornamented 

 character of its surface, in which point it shows some approach to the group of 

 G. inconstans, Phillips.^ 



We find the nearest approach to it in some Bohemian forms, especially in G. 

 bohemicus, Barrande,^ which differs in the ornamentation being much finer and 

 less arching, and the keel being broader. G. tabuloides, Barr.,^ and G. amosnus, 

 Barr.,* present the same differences, and are also much flatter shells. In G. 

 fecundus, Barr.,^ the ribs are coarser, fewer, and less arched, and the back is 

 flattened and not keeled. In G. Vanuxemi, Hall,^ which is closely allied to 

 Barrande's shells, the ornamentation is again finer, and the spire more discoid. 

 In G. simulator, Hall,^ the margins of the chambers are first bent forward and then 

 backward, so that the lobation was probably totally distinct. 



In G. {Tornoceras) siihundulatus, Freeh,** the stride are of quite a different 

 character ; the first bend forward is broader, the succeeding concavity is much wider 

 and more shallow, and the advance forward at the ventral elbow is not nearly so 

 great. Moreover, the umbilicus is smaller, the whorls are much wider, the shell is 

 almost involute, and the back is broader, and, as far as the figure goes, shows no 

 sign of a keel. Freeh states it to be a very variable shell ; but, though one of his 

 described varieties may vary in the direction of the present species, there can be, 

 I think, no doubt that the two forms are perfectly distinct. G. lamellosus, Sandb.,^ 



1 1841, Phillips, ' Pal. Foss,' p. 123, pi. li, fig. 238. 



2 1865, Barrande, ' Syst. Sil. Bohem.,' vol. ii, p. 29, pi. i, figs. 1—13, and pi. iii, figs. 15, 16, 

 Et. G. 



3 Ibid., p. 41, pi. iv, figs. 1—12, Et. G. 

 ■t Ibid., p. 28, pi. iv, figs. 13, 14, Et. G. 



5 Ibid., p. 32, pi. vii, figs. 10, 11 ; pi. xi, figs. 1—20, Bt. G-. 



" See under G. ohliquus, p. 58. 



^ 1879, Hall, ' Pal. N. Y.,' vol. v, pt. 2, p. 463, pi. ixix, figs. 1, 2, and pi. ixxiv, fig. 8. 



« 1887, Freeh, ' Zeitsch. Deutsch. Geol. Gesell.,' p. 465. 



'•• 1851, Sandberger, ' Verst. Khein. Nassau,' p. 85, pi. viii, figs. la—/. 



