ORTHOCERAS. 123 



wants the outer sliell and retains only the major series of longitudinal lines, which 

 appear thicker and more rounded than when seen in the external layer. 



Bemarhs. — These specimens appear to be portions of the body-chamber, and 

 therefore nothing is at present known of the septal part of the shell,^ but it seems 

 to have very distinct features. It is quite unlike any of the other species described 

 by Phillips from Devonshire, but approaches in some degree to the figure of 

 0. tuhicinella, Sowerby, given by Sandberger, so that Mr. Roberts and I were much 

 inclined to refer it to that shell as distinct from the original 0. tuhicinella of 

 Sowerby. As of the latter species, .with one exception, the septal portion is 

 only known, and as in the large specimen described below as 0. dolatum, 

 the rings become very indistinct toward the upper end-, it might be questioned 

 whether it might not be regarded as the body-chamber of that shell. I do not, 

 however, think that there is really room for this presumption, as the bulges are 

 very oblique, irregular, and confluent, so as to give the appearance of being 

 divided by slight, accidental, linear constrictions, rather than of being definite 

 swellings. The longitudinal lines, moreover, are very clear and prominent, and 

 the transverse striee are quite different from anything observable in 0. tuhicinella, 

 Sow., or its allies. Finally, the one specimen which I know of the body-whorl 

 of those shells preserves its specific characters with the exception that the rings 

 have become indistinct bulges. As Barrande has described a Bohemian species 

 under the name of 0. comatum,^ 1 am obliged to change the name which I 

 proposed in the ' Geological Magazine ' for the Devonshire form to 0. eutrichmn.- 



Affinities. — It is rather like 0. planicanaliculatiim, Sandberger,' but that shell 

 differs in having only one series of longitudinal ribs, which are stouter than in 

 ours, and in not having the transversely crumpled or tumid appearance described 

 above. It also tapers more rapidly. 0. costellatum, F. A. Romer,* which may be 

 the same as 0. planicanaliculatimi, Sandberger, has fewer, stouter, and more 

 regular radiations, and approaches in this respect nearer to the Lummaton cast 

 than to Mr. Champernowne's shell. In 0. striata -punctatum, Miinster,* and 

 0. originale, Barrande,* which taper more rapidly than do the English specimens, 

 the longitudinal lines are much coarser and more regular and parallel, as is shown 

 by examples in the British Museum. In the former of these shells they have a 



^ There is, however, in the Torquay Museum a small example of five segments of the apical end 

 of a Cephalopod which may possibly belong to this species. 



2 1868, Barrande, ' Syst. Sil. Boheme,' vol. ii, pt. 3, p. 401, pi. ccxcix, figs. 1—6. 



3 1852 ? Sandberger, ' Verst. Ehein. Nassau,' p. 161, pi. xviii, figs. 4 a—d. 

 * 1852, F. A. Eomer, ' Beitr.,' pt. 2, p. 92, pi. xiii, fig. 25. 



5 1840, Munster, ' Beitr.,' pt. 3, p. 101, pi. xx, figs. 1—3. 



6 1868, Barrande, ' Syst. Sil. Boheme,' vol. i, p. 206, pi. cclxvii, figs. 1—20, Et. D (colony) 

 and E. 



