ORTHOCERAS. 31 



Size. — One specimen about 3 mm. in width is 20 mm. long. The largest 

 fragment I have seen is about 11 mm. wide. 



Localities. — In the Barnstaple Atheneeum is a small specimen from Brushford ;. 

 in my Collection one from Ironpost near Dulverton, one from Frankmarsh, and one 

 from Upcott Arch Quarry ; in Miss Partridge's Collection one from Lower Orchard 

 Quarry. 



Remarks. — At first it seemed that two species were represented by these 

 fossils, the elevated annuli not being noticeable in the smaller specimens. After 

 a careful comparison, however, it appears that they are all identical. The annuli 

 probably became more prominent with the growth of the shell. They were 

 probably conterminous with the chambers, as in one instance they appear to 

 have been so, and if this is the case the height of the chambers varied from one 

 half to one quarter the width of the shell. The ornamentation though minute 

 is very definite, consisting of sh3,rp striations considerably more than their own 

 diameter apart and sometimes occurring in bands of three or four of greater 

 fineness than usual. 



Affinities. — From 0. lineare, Miinster,^ which is similarly lineated, this 

 species is distinguished by the possession of annuli. From 0. ibex, Sowerby,^ 

 and 0. articulatum, Sowerby,^ it differs in the absence of longitudinal strias. The 

 same character seems to distinguish it from all the American Devonian forms. 



0. tdbense, Tschernyschew,* agrees in form and rate of tapering ; but probably 

 differs in having fewer minor strige, and wider and more horizontal chambers, and 

 in being larger. 



0. vertehratum^ Sandberger,^ appears to differ in the striae being intermittent^ 

 and perhaps in the annuli being larger. 



4. Oethocbras vennense, Foord. 



1840. Oethoceeas cxlindraceum, Sowerly. Geol. Trans., ser. 2, vol. v, p. 703,* 



pi. Hi, figs. 6, 7. 



1841. — — Phillips. Pal. Foss., p. 113, pi. xliii, figs.. 



213 a—c. 



1888. — TENNEKSE, Foord. Catal. Foss. Cepbal., vol. i, p. 85. 



1 1840, Miinster, ' Beitr.,' pt. 3, p. 99, pi. xix, fig. 1. 



2 1839, Sowerby, in Murch. ' Sil. Syst.,' p. 613, pi. v, fig. 30. 



3 Ibid., p. 613, pi. V, fig. 31. 



* 1893, Tschernyschew, ' Verhandl. Euss. Miner. Gesell.,' vol. xxx, p. 18, pi. iii, figs. \a I. 

 5 1853, Sandberger, ' Verst. Ehein. Nassau,' p. 170, pi. xx, figs. 3 — 3 c; and 1876, Maurer, 

 ' Neues Jahrb. f. Min.,' Ann. 1876, pp. 12 and 23. 



