72 DEVONIAN FAUNA. 



species, G. bilanceolatus,^ which has a much smaller umbilicus than ours. Tietze/ 

 however, remarks that Sandberger's G. bilanceolatus is without doubt the same 

 species as G. Mmisteri, and gives a good figure, which has no visible umbilicus, and 

 shows that its whorls do not rise so convexly from the centre as they do in ours ; 

 and thus it is proved to be distinct. 



G. Verneuili, Miinster,^ seems in some respects still more similar than G. orbicu- 

 laris, as it is a much smaller shell, and has a comparatively larger umbilicus than 

 that species. It has a definitely flattened back similar to that of G. ohliquus, 

 Whidborne. I doubt whether the British specimen has this feature, and it differs 

 in being more comj)letely involute. 



G. orbiculus (Beyrich)* is distinguished by being only partially involute, thus 

 having a wide umbilicus instead of a very small one, but in other respects it 

 appears to correspond. It also resembles in some degree G. Ungeri, Miinster,^ 

 but shows no trace of the radiating ridges seen in that species. 



10. GoNiATiTES PSiTTAOiNus, WliicTbome. PI. VI, figs. 9 — 13. 



1888. GrONiATiTES psiTTACiNTTs, WMdlome. Geol. Mag., dec. 3, vol. vi, p. 29. 



Descriptio7i. — Shell oval, convex, elliptic, transverse ; of small size. Umbilicus 

 deep and minute, but almost always closed by the margin of the body-whorl. 

 Whorls apparently few. Chambers narrow. Inner whorl occupying about two- 

 thirds of the diameter of the mouth. Sides of the whorls flat for about half their 

 diameter, and then rounding over the back with a nearly circular curvature. No 

 signs of any keel. Surface apparently smooth. Suture-line with a small sharp 

 central lobe, shallow arched central saddles, and very wide rounded lateral lobes 

 coming much in advance of the central lobe, and being much steeper on the 

 ventral than on the dorsal side ; lateral saddles small and arched. 



Size. — Mr. Vicary's largest specimen measures 45 mm. in height, 35 mm. in 

 width, and 19 mm. in depth ; but the general run of the specimens is not more 

 than 20 mm. in height. 



Locality. — Wolborough. There are thirteen specimens in Mr. Vicary's Collection, 

 three in the Torquay Museum, three in the Museum of Practical Geology, and 

 two in the British Museum. 



Remarks. — This is a very curious and distinctive form. It appears sufficiently 

 common at Wolborough, but I have never found any trace of it at Lummaton. It 



^ 1851, Sandberger, ' Verst. Eheiu. Nassau,' p. 71, pi. viii, fig. 11, and pi. ix, fig. 7. 



2 Tietze, ' Devon. Schichten von Ebersdorf ,' p. 28, pi. i, fig. 7. 



3 1839. Miinster, ' Beitr.,' pt. 1, p. 17, pi. iii, fig. 9. 



* 1837, Beyr., ' Beitr. Khein. Ubergangsg.,' p. 36, pi. ii, figs. 4 a, b. 

 » 1840, Munster, ' Beitr.,' pt. 3, p. 107, pi. xvi, figs. 8 a—c. 



