144 DEVONIAN FAUNA. 



Sow.), and has the narrowest chambers of those species which Miinster figures, the 

 septa are decidedly more distant. 



Orthoceras cf . planosej)tatum, Sandberger, is a specimen figured by Beushausen^ 

 as a cast. It only difi'ers from this form by the somewhat greater depth of its 

 septa, their ratio to the width being only 1 : 8 instead of 1 : 12. 



0. Kossvx, Tschern,,^ has slightly wider chambers, and a more excentric 

 siphuncle. It is a very large shell with a large body-chamber, but its surface is 

 unseen. 



0. excentricimi, Sowerby, has, according to Blake,^ flatter and more distant 

 septa ; and, as figured by the same author, 0. imbricatiim, Wahlenberg,* has 

 decidedly more distant septa and increases much more slowly, so that it evidently 

 is distinct. 0. perversum, Blake,^ comes nearer in the closeness of the septa, but 

 still differs in being almost cylindrical. 



13. Orthoceeas laterale, Phillips. PI. XV, figs. 1 — 5. 



Oethoceea, sp., Hennali. Lime Rocks of Plymouth, pi. viii, fie;. 3. 

 1841. Orthoceeas lateeale, Phil. Pal. Foss., p. 110, pi. xli, figs. 205 a — e. 

 ? 1852 ? — siMPLicissiMUM, Sandb. Verst. Rhein. Nassau, p. 172, pi. xx 



figs. 7 a, h. 

 ? 1852. — MTJLTiSEPTATTTM, F. A. E'um. Beitr., pt. 2, p. 80, pi. xii, 



figs. 21 a, h. 

 1855. _ _ _ Ibid., pt. 3, p. 36, pi. vii, 



fig. 10. 

 1867. — Geujtdense, Trenkn. Palaont. Nov., pt. 2, p. 21, pi. vii, 



fig. 11. 

 1884. — GrEUNDENSE, Clarke. Neues Jahrb. f. Min., &c., p. 334, pi. iv, 



figs. 7—9. 

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



1888. — — ? Foord. Cat, Foss. Cepb. Brit. Mus., vol. i, p. 86. 



Description. — Shell elongate, tapering, sometimes very large ; very slightly 

 arched, so that the ventral side is very slightly convex, and the dorsal slightly 

 concave ; upper part slightly expanding. Rate of tapering, 1 in 7 or 1 in 8. Apex 

 very small, possibly acuminate. Section slightly elliptic. Siphuncle central, 

 small. Chambers very concave, rather narrow, about five or six times as wide as 



1 1884, Beushausen, ' Abbandl. Geol. Specialk. Preussen,' Band V\, pt. 1, p. 41, pi. vi, fig. 14, 



2 1887, Tschernyschew, ' Mem. Com. Geol.,' vol. iii, pt. 3, pi. clxix, t. 3, figs. 1 a — c. 



3 1882, Blake, ' Mon. Brit. Foss. Ceph.,' pt. 1, p. 152, pi. xii, fig. 2. 

 * Ibid., p. 153, pi. xiv, figs. 1, 3—6. 



'" Ibid., p. 155, pi. xvi, figs. 1. 2. 



