58 DEVONIAN FAUNA. 



very nearly in many points. In that form the umbilicus seems rather small, the 

 inner whorls are nodulous rather than ribbed, and the septal lines are more sickle- 

 shaped. Miinster describes the back as very small and flat, and probably it is 

 much narrower than that of our species. None of the other species described by 

 Miinster, Geinitz, or Sandberger at all approach it. 



Under G. evexus, von Buch, Kayser^ unites many shells, including A. Dannen- 

 bergi, Beyr., G. costulatus, d'Arch. and de Vern., G. transitorius, Phil., and F. A. 

 Romer, G. expansus, Vanux., and G. verna and fecundus, Barrande. It appears to 

 me that our present form is clearly distinguished from von Buch's shell as described 

 by Kayser by the shape of the septa, which are much more oblique and have a 

 sharp angular central saddle before turning to the back, while Phillips's G. tran- 

 sitorius is also distinguishable by its more open umbilicus, more oblique septa, and 

 more slowly increasing whorls. I am not of opinion that either of these English 

 forms agree with von Buch's shell, although they evidently belong to the same 

 group of Goniatites. 



In G. Dannenhergi (Beyr.),^ the section of the whorls is short and convex, and 

 it is not at all involute. The suture-line, however, is very similar to that of the 

 present species. G. expansus, Vanuxem,^ afterwards described by Hall (who states 

 it to be different from G. expansus, von Buch)* as G. Vanuxemi,^ difiers in having 

 the lateral saddle much deeper, so that the sides of the chambers do not tend at 

 once forwards as they do in G. ohliquus. Hall gives a figure of a young specimen 

 which almost exactly corresponds with our figured specimens of G. transitorius, 

 Phil., and traces the changes of form in the American shell which occur with age. 

 This may show that some at least of the American examples belong to Phillips's shell; 

 but I do not regard it as at all likely that it indicates "that the two English forms 

 belong to a single species, for small shells of G. ohliquus present the same characters 

 as the larger specimens, and moreover appear very distinct from the examples of 

 G. transitorius of a similar size. Hall remarks upon the proximity of his species 

 to G. Bohemicus, Barr.,^ and this differs from the present species still more than 

 does the American shell, and indeed comes nearer to G. fidguralis than to G- 

 ohliquus. G. Noeggerathi, von Buch,^ and G. evexus, von Buch,^ appear, as far as can 

 be judged from the evidently inaccurate figures by their original describer, to be 



1 1878, Kayser, 'Abhand. Geol. Specialk. Preussen,' Band iii, pt. 2, p. 58, pi. viii, figs. 4 — 7. 



2 1837, Beyrich, ' Beitr. Rheiu. tJbergangsg.,' p. 26, pi. i, figs. 5 a, h. 



3 1842, Vanuxem, ' Geol. Siirv. JST. T. Eept., 3rd Dist.,' p. 146, fig. 1. 

 * 1832, von Buch., ' Uber Amm. und Gon.,' p. 31, ])1. i, figs. 1, 2. 



5 1879, Hall, ' Pal. N. T.,' vol. v, pt. 2, p. 434, pis. Ixvi— Ixviii ; pi. Ixix, figs. 3—6; pi. cix, 

 figs. 7, 8. 



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



7 1832, von Buch, ' Uber Amm. und Gon.,' p. 34, pi. i, figs. 6—8. 



8 Ibid., p. 33, pi. i, figs. 3—5. 



