68 
XAUTILOIDKA. 
? 1878. Orthoceras canaliculatum, Haupt, Die Fauna ties Graptolithen- 
Gesteines, p. 55. 
1882. Orthoceras angulatum, Blake, British Foss. Ceph. pt. i. p. 106) 
pi. vii. if. 4, 8, 9. 
8p. Char. Shell straight or slightly curved. Section circular. 
Rate of increase about 1 in 8. Body-chamber not precisely known 
from the British examples, but in the Bohemian ones it attains a 
length equivalent to about twice the diameter of its base. Septa 
distant about ^ the diameter of the shell. Siphuncle central. 
The principal ornaments consist of a series of prominent longi- 
tudinal ribs upon the surface of the shell, which are sufficiently 
strong to mark the cast very distinctly. Between these, very fine 
riblets or raised thread-like lines are sometimes, but not always 
present. Between the ribs there are fine transverse arched striae 
which pass over the riblets when these are present. In a Bohemian 
specimen having a diameter of 14 lines the ribs have a maximum 
distance of 2 lines, and in a British example with a diameter of 10 
lines they are from 1| to l.L line apart. The finer ornaments of 
the test do not appear to have been preserved in any British 
specimens. 
Horizon. Wenlock Shales. Etage E, bandc e 2 ( = Salopian). 
Localities. British. Ledbury, Herefordshire. — Foreie/n. Wis- 
kocilka, Bohemia. A fine specimen from the Lower Ludlow, at Usk, 
Monmouthshire, has been presented to the Museum by J. E. Lee, 
Esq., F.S.A., F.G.S. 
Var. spectandoim, Blake. 
1882. Orthoceras filosum^ Sow., var. sjtecfamlnm, Blake, British Foss. 
Ceph. pt. i. p. 114, pi. vii. f. 12. 
The ornamentation of this variety connects it, in my judgment, 
rather with that group of species (of which 0. canaliculatum is 
amongst the number) which centres around 0. angulatum than with 
O.filosum. From the latter it difiers in having smaller (riblets) 
alternating with the larger ribs, a feature which at once reminds 
one of 0. angulatum and its congeners. It resembles 0. 
Barraiide, in the fineness of its ribbing, and in the possession of 
transverse striae, which are rarely present in O.Jilosum. On the 
whole, therefore, I think the place of this interesting variety is 
near to 0. canaliculatum. v 
The specimen in the National Collection is a fragment of the 
test. 
