ORTHOCERAS. 153 



they all belong to the same species ; but they do not seem to agree with any of 

 the other species from the localities under notice. In only one of these specimens 

 can the width of a chamber be seen, and this is very narrow ; but it is often the 

 case, as noted by Mr. Bather in the 'Geological Magazine' for October, 1887, 

 p. 449, that the first chamber of a Cephalopod is narrower than the rest ; and 

 therefore no deduction of their general width can in this case be made. They are 

 not easily comparable with the fossils which above I have united to Phillips's last- 

 mentioned species, under the name oi Actinoceras devonicans, n. sp.,^ as they belong 

 for the most part to a different portion of the shell. They seem, however, to 

 differ from them generically, as well as specifically, on account of the small size of 

 their siphuncle, and of their section being decidedly more circular. 



On the other hand, the present species appears to agree, as far as can be 

 judged from our defective specimens, with 0. acuminatum, Bichwald," but here 

 again we have not sufficient data to form a decided opinion. As so few species 

 have hitherto been proved to be common to the Devonian Formations of England 

 and Russia, the presumption is, on general grounds, against their identity, when it 

 is remembered that there are many features, not observable in our fossils, in which 

 there is room for specific divergency between the two forms. 



Affinities. — From 0. Ludense, Sowerby^ (not Phillips), it is distinctly different, 

 not being, for instance, circular in section. 



0. crassum, F. A. Romer,* as figured by Tietze,^ is distinguished by being 

 widely oval instead of moderately elliptic in section ; but, as given by Sandberger,® 

 it differs in being quite circular instead of elliptic, and in having the margins of 

 the septa straight instead of oblique. 



From 0. Bohertsii it differs in not having a circular section, and in its surface 

 being in all probability smooth. 



NOTE. 



As the localities, with which we are now dealing, have proved to be so prolific 

 in Cephalopods, it may be interesting at the present point to review the species of 

 this class which have been elsewhere recorded from the South of England. 



In 1840 Sowerby described seven species by name, viz. Orthoceras cylindraceum,^ 



1 See above, p. 120. 



2 1860, Eichvvald, ' Lethaea Eossica,' vol. i, p. 1215, pi. xlix, fig. (3. 



3 1839, Sowerby in Murch. ' Sil. Syst.,' p. G19, pi. ix, fig. 1. 

 * 1843, F. A. Eorner, ' Verst. Harz.,' p. 35, pi. x, fig. 6. 



^ 1870, Tietze, ' Uber Devon. Schiclit. Ebersdorf,' p. 36. pi. i, fig. 17. 

 ^ 1852 ?, Sandberger, ' Verst Eliein. Nassau,' p. 162, pi. xix, figs. 1, 1 a. 



7 1840, Sow., ' Greol. Trans.,' ser. 2, vol. v, pt. 3, pi. lii, figs. 6 and 7, and pi. Ivii, fig. 28. The 

 last of these figures, which is from a Newton specimen, is evidently difi'ei'ent from the rest, and 



