142 DEVONIAN FAUNA. 



12. Obthoceras Champernowni, n. sp. PI. XV, figs. 11, 11 a, 12. 



1841. Oethoceeas imbeicatum, PJiil. (not WaJilenlerg) . Pal. Toss., p. Ill, 



pi. xlii, fig. 207. 

 1853. — — Steininger. G-eogn. Beschr. Eifel., p. 39. 



1855. — SowEEBTi, ? M'Coy. Brit. Pal. Fobs., pt. 3, p. 573. 



1878, — sp., Kayser. Abhandl. Specialk. Preuss., Band iv, pt. 2, 



pi. xi, fig. 7. 



1888. — IMBEICATUM, EtJieridge. Poss. Brit., pt. 1, Pal., p. 168. 



1889. AcTiNOCEEAS SowEEBTi,? Foord. Cat. Foss. Ceph. Brit. Mus., pt. 1, p. 191. 



Description. — Shell large or of medium size, straight, nearly cylindrical in the 

 body-chamber, rapidly tapering in the septal portion. Rate of tapering 1 : 6. 

 Septa very close, moderately concave, slightly oblique, with arched edges. 

 Distance of septa only one-twelfth of their width. Siphuncle slightly excentric, 

 large, and somewhat beaded by the edges of the septa. Section slightly elliptic, 

 with diameters as 15 : 16. Surface unknown. 



Size. — Mr. Champernowne's specimen is 55 mm. long, 23 mm. wide at the oral, 

 and 13 mm. at the apical, extremity. 



Locality. — Wolborough. There is a beautiful specimen, sliced and polished, 

 in Mr. Champernowne's Collection ; a rather fragmentary specimen which shows 

 the exterior is in Mr. Vicary's Collection, another in the Torquay Museum, and 

 two more in the Museum of Practical Geology. 



Remarks. — The specimen figured by Phillips is much larger than any which 

 I have myself seen, but otherwise it accurately corresponds with them. He 

 states the section to be elliptic, with diameters in the ratio of 10 : 12. I am not 

 acquainted with the surface ornamentation, and am not very certain about the 

 identity of the two specimens in the Torquay and Vicary Collections, which I 

 have not lately had the opportunity of examining. 



As 0. imbricatum, Wahl.,^ is a Silurian species the question arises as to the 

 correctness of Phillips's determination. To Sowerby's figure,^ given in the 

 ' Silurian System,' it bears a strong resemblance, the differences being that the 

 Silurian species is of a more regular conical form, not so cylindrical on the body- 

 chamber, and tapering more slowly in the septal part, and that its septa are slightly 

 more oblique and rather wider, bearing a relation to the diameter of about 1 to 10. 

 Thus it is most probably distinct. Mr. Foord^ has dwelt at length upon the various 

 species that have been at various times included under the name 0. imbricatum, 

 and the result is to leave the present species without an appellation. Thus we find 



^ 1821, Wahlenberg, ' Nova Acta Eeg. Soc. Sc. TJpsal.,' vol. viii, p. 89. 



2 1839, Sowerby in Murcb., ' Sil. Syst.,' p. 620, pi. ix, fig. 2. 



3 1888, Poord, 'Cat. Poss. Ceph. Brit. Mus.,' pt. 1, pp. 19, 181, 191. 



