140 DEVONIAN PAUNA. 



indeed, much more resemblance to the Devonshire shell than has his 0. suhannulare, 

 although its ornamentation is finer and its siphuncle not quite central, and I am 

 much inclined to regard it as a variety. To sum up, while Miinster's original 

 description of his Devonian shell agrees exactly, as far as it goes, with our shell, 

 the interpretations of it by M'Coy, Barrande, and Foord, referring chiefly to the 

 form occurring in the Silurian beds, present some points of difficulty which raise a 

 strong doubt as to the identity of the Silurian form with Miinster's, and which do 

 not appear to arise in another Devonian species described by the Bohemian 

 author. Lastly, 0. Wissemhachii, d'Arch. and de Vern.,^ as given by F. A. Romer, 

 appears so similar as to cause a presumption of its identity, its rings being much 

 closer and its size much greater than in d'Archiac's type, and, moreover, bearing 

 secondary striae. The specimen, however, which Romer figures, is a small fragment 

 showing few specific characters. 



Affinities. — Our shell comes very close to 0. annulatum, Sow.,^ but its septa 

 and ribs are wider apart, its riblets are closer, more numerous, and less fimbriated 

 and foliaceous, and its longitudinal mai-ks are always almost invisible. These 

 differences are clearly shown in Blake's^ figures of Sowerby's fossil, its small 

 flounced riblets marking it as specifically distinct. 



0. vertehratum, Sandberger,* has the rings much more rounded and more 

 distant, so that the distances of the septa, which are half as numerous as the rings, 

 are equal to the width of the shell. 0. solitarium, Barrande,^ has a very excentric 

 siphuncle and much narrower chambers. 



0. Agassizi, Barrande,^ has an excentric siphuncle and no longitudinal 

 imbrications. 



11. Orthocbeas ortx, n. sp. PI. XIV, figs. 9, 9 a, 9 h, 9 c. 



1841. Oethocebas ibex, Phillips (not Sow.). Pal. Toss., p. Ill, pi. xliii, 



fig. 208. 

 1888. — — Etheridge. Foss. Brit., pt. 1, Pal., p. 168. 



Description. — Shell elongate, small, not tapering much. Section oval. Septa ? 

 Siphuncle central {fide Phillips). Surface with numerous prominent arching 



1 1842, D'Arch. and de Vera., ' Geol. Trans.,' ser. 2, vol. vi, pt. 2, p. 345, pi. xxvii, fig. 3. 



2 1818, Sow., ' Min. Conch.,' vol. ii, p. 73, pi. cxxxiii ; and 1889, Foord, ' Cat. Ceph. Brit. Mus.,' 

 vol. i, p. 53. 



8 1882, Blake, ' Mon. Brit. Foss. Ceph.,' pt. 1, p. 89, pi. iv, figs. 1—8; and pi. viii, figs. 1, 3. 

 * 1852 ?, Sandberger, ' Verst. Ehein. Nassau,' p. 170, pi. xx, figs. 3 a—c. 

 5 18G8, Barrande, ' Syst. Sil. Boheme,' vol. ii, pt. 3, p. 267, pi. cclxxix, figs. 32—37, Et. E. 

 « 1866, Ibid., p. 299, pi. cclxxxi, figs. 1—18, &c., Et. E and G. 



