104 DEVONIA.N FAUNA. 



appears to be nearly perfect, and probably is a full-grown though small shell. 

 Just before the commencement of the body-chamber the ribs become suddenly 

 so much coarser as to approximate very closely to G. jimbriatum, Ph.^ 



It appears to me that, as far as can be judged from his figure and description, 

 the C. undulatum of F. A. Romer belongs to the present form. He there 

 describes the chambers as six times as wide as high, but this ratio decreases 

 towards the apical end. In none of the English specimens which I have seen are 

 the chambers shown, but in the kindred species they bear a similar relation. 



Affinities. — G. alticola, Barrande,^ is straighter, and its transverse ribs are 

 straight, fine, and not foliaceous. 



G. tessellatum, de Koninck, from the Carboniferous of Vise, has, according to 

 Ferd. Romer, ^ very much stronger radiating ridges, 



G. cinctum, Mlinster,* from Tournay, has very much closer, finer ridges, and 

 shows no traces either of a ventral sinus or of longitudinal markings. 



G. morsum, Hall,^ is figured from a very much worn specimen. Its only dis- 

 tinction from the English species appears to be the absence of longitudinal linea- 

 tions in the American form ; should these prove to be present in better-preserved 

 examples, Hall's name would have to be regarded as a synonym of Phillips's. 



2. CYRTOCEJiAS (?) FIMBRIATUM, PMlUpS. PI. X, figS. 3, 3 ft, 4, 4 a. 



1841. Ctetoceras fimbeiatum, Phil. Pal. Foss., p. 114, pi. xliv, fig. 214. 



1842. Ctbthoceeatites fimbeiatus, D'Arch. and de Vern. Geol. Trans., ser. ii, 



vol. vi, pt. 2, p. 386. 

 1849. Ctetoceeas fimbeiatus, D'Orhigny. Prodrome, vol. i, p. 53. 

 1852. — FIMBEIATUM, Oiehel. Pauna der Vorwelt, Band 3, Abth. 1, 



p. 206. 

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



1888. — ? — Foord. Cat. Foss. Ceph. Brit. Mus.,pt. 1, p.817. 



Description. — Shell elongate, flattened, regularly tapering; considerably arched 

 in the ventro-dorsal aspect, the curvature being greatest in the apical, and almost 

 vanishing in the oral region ; laterally deflected, so that the right-hand side is 

 almost straight, and the left-hand side very oblique. Upon a chord of 55 mm. 

 subtending the concave side the greatest curvature is 8 mm. Section having 

 ventro-dorsal to transverse axis in the ratio of about 15 : 20, near the mouth, but 

 becoming nearly circular at apex. Chambers about sixteen, narrow, very concave. 



^ See remarks under that species, p. 106. 



- 1887, Freeh, ' Zeitsch. deutsch. geol. Gesell.,' p. 730, pi. xxxviii, fig. 2, and pi. xxxis, figs. Ida, b. 



■^ 1876, Ferd. Komer, ' Leth. Pal.,' pi. xlvi, fig. 2. 



* 1839, Miinster, ' Beitr.,' pt. 1, p. 34, pi. ii, fig. 4. 



■> 1879, Hall, ' Pal. N. Y.,' vol. v, pt. 2, p. 3U7, pi. xlvii, figs. 4, 5. 



