68 
NAUTILOIDEA. 
1873. Orthoceras annulatum, var. fimbriatum, Salter, Cat. Cambr. and 
Sil. Foss. p. 158. 
1882. Orthoceras fimbriatum, Blake, British Foss. Ceph. pt. i. p. 115, 
pi. viii. ff. 1, 3 {not f. 2). 
This variety is distinguished from the species by superficial cha- 
racters. Whereas in the latter the transverse ribs predominate, in 
the variety the longitudinal elevations come into prominence, though 
I have not seen any specimens in which the transverse annulations 
are wholly suppressed. The arches or festoons of the fimbriae lie, 
as a rule, if not invariably, in the shallow furrows between the 
longitudinal flattish elevations. The fimbriae do not differ materially 
in character from those of the species. 
I am not prepared, without more satisfactory evidence than is at 
present available, to accept the conclusion come to by Messrs. Salter 
and Blake that 0. Brifiitii Sow., is identical with the present 
variety. None of the specimens of 0. Brujlitii that I have seen, 
either in the National Collection or in the Museum of Practical 
Geology, show the slightest vestige of the test, its position being 
indicated only by a very thin dark line, the whole of the interior of 
the shell, except the siphuncle, being filled with crystalline calcite. 
Horizon. Wenlock Shales, Upper Ludlow (Salopian and Down- 
tonian). 
Localities. British. Dudley, Worcestershire. — Foreign. Wisby, 
Island of Gothland, Sweden. 
Yar. subtile, var. nov. 
This differs from the last, to which, however, it is closely allied, 
in the extreme fineness of the fimbriae. Faint annulations occur at 
tolerably regular intervals of about 3 J to 4 lines. The fimbriae are 
more crowded upon the annulations than they are in the interspaces, 
just as is the case in 0. annulatum. Longitudinal elevations are 
always present as in the latter. 
There is an intermediate form in which the fimbriae are neither 
so coarse as in the variety fimbriatum, nor so fine as in the one 
under discussion. Its afiinities seem to be, on the whole, rather 
with the latter : it is represented in the Collection by a specimen 
from the Island of Gothland, and by another from Dudley. 
Horizon. Wenlock Shales, Upper Ludlow (Salopian and Down- 
tonian). 
Localities. British. Dudley, Worcestershire ; Herefordshire (?). — 
Foreign. Wisby, Island of Gothland, Sweden. 
Sowerby, in Murchison’s Sil. Syst. p. 626, pi. xii. f. 21. 
