XXII 
ON PTERASPIS DUNENSIS (ARCHAOTEUTHIS 
DUNENSIS, ROEMER),. 
Quarterly Journal of the Geological Society of London, vol. xvii., 1861, 
pp. 163—166. (Read January 23, 1861.) 
THE fourth volume! of the ‘Paleontographica’ of Dunker and 
Von Meyer (1856) contains a memoir on “ Palgoteuthis, a genus of 
Naked Cephalopoda from the Devonian rocks of the Eifel,” by the 
well-known paleontologist, Dr. Ferd. Roemer. The fossil upon which 
this genus is founded is described as an oval, convex, symmetrical, 
shield-like body, marked by two diverging longitudinal elevations 
or keels, and exhibiting on its surface a peculiar ornamentation, 
consisting of curved parallel ridges, so fine that there are as many 
as 8 or 10 toaline. All traces of any deeper layer than that which 
exhibits these ridges had disappeared. In discussing the affinities 
of this fossil, Dr. Roemer decides in favour of its being the internal 
shell of a Naked Cephalopod, upon the grounds, first, of its general 
form, and, secondly, of the presence: of the diverging keels, in both 
of which respects he considers the fossil to resemble the internal 
shell of a Sepéa. And he adds: “Inasmuch as the fine superficial 
sculpture is altogether peculiar and different from that of the cuttle- 
bone, and since, further, the fact that the fossil exhibits such a 
structure only upon its surface leads one to suspect that it was not a 
thick ossicle, but thin and horny like that of Zoézgo, and since, finally, 
its occurrence in so old a formation makes its generic identity with 
the living genus improbable, it will be justifiable to consider the fossil 
as the type of a new genus, although its clear definition can only be 
rendered possible by the discovery of more perfect specimens, and 
perhaps of other parts of the animal” (p. 74). 
1 Page 72, plate 13. 
VOL. II EE 
