E^'DOCERATID^. 
141 
the shell. Test very thin ; composed of two or more layers, the in- 
ternal one being covered transversely with minute incised, inter- 
rupted lines ; the outer with very fine raised lines or riblets, about 
half a line apart, these being crossed longitudinally by still finer 
lines, which can only be seen with a lens. These last are very 
obscure. 
Remarhs. Eichwald has pointed out the mistake into which many 
authors have fallen in identifying this species with E. troclileare, 
Dalman. No doubt, as Eichwald observes, authors have been led 
into this error by Hisinger (Lethsea Svecica, p. 28), who adds to 
his description of E. troclileare the words “ Orthoceras vaginatus ?, 
Schloth.” In point of fact E. vaginatam appears to have been over- 
looked by palaeontologists until it was brought to light again and 
properly described and figured by Eichwald. It wiU be interesting 
to give here the main points of his description. The principal cha- 
racter of the species, he says, which was known to M. de Schlotheim 
only from Reval [Esthonia], is the possession of a nearly cylindrical 
shell, pierced by a large siphuncle, which attains at least half the 
width of the shell, goes along its margin, enlarging rather rapidly, 
so that it finally occupies nearly three fourths the width of the 
shell; it is fixed, as M. de Schlotheim expresses it, like a sword in 
its sheath ; the surface of the test is transversely striated with 
very fine, close-set, slightly raised striae. 
These are the characters which suffice to distinguish our species 
from troclileare^ cancellatum, and species provided with distinct 
transverse ribs, of which no mention is made in M. de Schlotheim’s 
description. One of the principal characters of this species is the 
large and thick siphuncle, which generally exceeds half the width 
of the shell, which is not the case either with troclileare or with 
cancellatiim, or with any other species of Orthoceras near to vagi- 
natum. {Eichwald.) 
The single specimen of E. vaginatum in the collection bears out 
the foregoing description. It is a fragment of the septate portion 
of the shell, about 5 inches in length, having a diameter of about 
1 inch at the smaller, and nearly I| inch at the larger extremity. 
This is apparently a rare species. Eichwald observes that he is 
not aware that it has been found in Sweden, or, indeed, anywhere 
except in Esthonia. 
Horizon. Orthoceras-lAmQiiio'n.e ( = Arenig). 
Locality. Reval (Esthonia), Russia. 
The Collection contains one example, presented by A. H. Foord, 
