SUPPLEMENT. 
331 
that the small faces of the pyramid are curved, but the large face 
flat. Notwithstanding the absence of the shell, there may still be 
observed flue, irregular, slightly prominent striae, which upon each 
of the lateral faces rise towards the dorsal keel, forming with the 
suture of the septa an angle of 45°, and then pass over the ventral 
face, where they describe a curve whose convexity seems turned 
towards the summit. Septa triangular, rounded, concave, with 
slightly undulated edges, the latter turning forwards a little upon 
each angle or keel, then turning backwards again in passing over 
the face. Height of the chambers variable, but they are generally 
xery low, as eighteen may be counted in a space equal to the width 
of one of the smaller sides. Siphon circular, rather large, placed 
against the middle of the larger side and opposite to the right angle 
of the pyramid. 
“ This gigantic species was at least two metres in length ; the 
fragment we possess, and which could not be flgured entire, measures 
0*36 [of a metre]. AVe have seen at Wurzbourg, in the possession 
of Professor Landaberger, a specimen of this OrfJwceratite, upon 
which are wide, rounded, slightly raised folds, corresponding to 
swellings or nodosities, xflaced upon the principal keel ; in the 
specimen which we have represented there are only slight indica- 
tions of these folds, which must undoubtedly be more prominent 
towards the summit of the shell than at the anterior part, the only 
portion which we have.’' (cVArcliiac and de Venieuil.) 
Eemarl’s. This species was afterwards described and flgured by 
the brothers Sandberger, who represent a young specimen with 
sculpture such as that mentioned in the above description of the 
fossil. These ornaments are also described by Kayser, who ob- 
served them in a specimen from the Rhenish Schiefergebirge, and 
in a variety which he describes under the name of Bidcemis (loc. 
cii. 1878, Taf. xi. flg. 2) they are very strongly marked. This author 
remarks upon the wide distribution of J. triangularis, which occurs 
at Wissenbach, Haiger, and Cramberg, in Orthocerasschiefer (Lower 
Devonian) ; Hausen, near Butzbach, in similar deposits ; Xieder- 
lahnstein and Laubbach, near Cobleutz, in Spiriferensandstein 
(Lower Devonian) ; and at Gerolstein in the Eifel (Hiddle 
Devonian). 
A fragmentary specimen in the National Collection from the Wis- 
senbach Slates has much wider septa than the type figured by 
d’Archiac and de Yerneuil, or any of the individuals figured by G. 
and F. Sandberger ; it may therefore be regarded as a variety, and 
I would suggest the name latiseptatum for it. The distance of the 
septa in this variety is equal to ^ of the corresponding diameter of 
