150 
NAUTILOIDEA. 
the siphuncular aspect of the shell ; distant from to 3 lines, where 
the longer diameter is 23 lines. Siphuncle marginal, its diameter 
I that of the longer diameter of the shell, where the latter has a 
diameter of 21 lines. Ornamentation consisting of coarse annula- 
tions divided by spaces of about equal breadth. Distance between 
the annulations from 3| to 4^ lines. The annulations and their 
interspaces are covered transversely by very distinct riblets, running 
parallel to them. About six of these riblets are contained in the 
space of 2 lines. The whole is crossed longitudinally by fine thread- 
like lines which can only be detected with a lens. 
Uemarlcs. This is a well characterized species, and is distinguished 
from E. troclileare, its nearest ally, by its subelliptical section, slightly 
fiattened on the siphuncular side, coarser and more distant annula- 
tions, as well as stronger and more distant riblets. 
The fine longitudinal striae described by Eichwald as occurring 
beneath the external layer of the shell cannot be regarded as of 
specific importance, as the same markings are met with in E. troch- 
leare. The name cancellatum was therefore rather unfortunately 
chosen for this species. Fischer s figures (loc. cii.) very probably 
represent a species identical with the present one. That author 
knew neither the locality nor the horizon whence his form was 
obtained. 
Horizon. Or^/iocern^-Limestone ( = Arenig). 
Locality. Eeval (Esthonia), Eussia. 
Eepresented by two imperfect specimens, which, however, show 
the essential characters of the species. 
Endoceras festinans, Blake. 
1882. Orthoceras {Endoceras) festinans, Blake, British Foss. Ceph. pt. i. 
p. 163, pi. xvii. ff. 3, 3 a. 
Sp. Char. “ The section is not quite regular, and the specimen 
may have been therefore somewhat compressed ; at present it 
is elliptic, having the radii in the ratio of 4 to 5. The rate of increase 
of the long diameter is 2 in 15. No body-chamber or ornaments 
are seen. The septa are slightly undulating, and are distant 
the diameter. They form long necks in the neighbourhood of the 
siphuncle, which they are seen to cross on the worn surface at a 
distance of one chamber towards the apex. Their convexity is 
about 1 the diameter. The siphuncle is cylindrical, having a 
diameter of | the longer diameter of the shell; it lies close against 
the side on the shorter diameter.” {Blake.) The length of the shell 
is 3| inches, and the greatest diameter 3^ inches. 
