332 
DEVONIAN FAUNA. 
the English and German forms. Both Mr. T. Roberts and Mr. R. B. Newton 
have verijfied and agree with this identification. 
Affinities. — Porcellia primordialis, Schlotheim, sp.,^ is the species which appears 
to be most nearly allied to the present. It seems to be a somewhat variable form, 
and the question arises whether the variation is so great as to include Sandberger's 
species within its limits. In considering this question I have had the advantage 
of the help of Mr, Newton, and we both have come to the same conclusion. 
Schlotheim's figure of his Ammo7iites jyvvniordialis is so bad that his species can 
only be identified by the help of his description. F. A. Romer/ however, under 
the name Belleroplion primordiaUs, Schlotheim, sp., gives several figures which 
show that typically the species is finely cancellated, but that occasionally the 
spiral lines are almost invisible especially in young individuals. In his later work 
he figures under the name of Schizostoma carinatum,^ a shell which shows the 
spiral striping and seems to be a young example of the same species, though it 
appears in the figure slightly sub-discoidal. Lastly Clarke* describes Porcellia 
primordialis, Schlotheim, sp., as having spiral lines, though occasionally only 
radiating lines are visible. In the British Museum are several German specimens 
of P. primordialis which show the spiral striae more or less distinctly in shells of 
all sizes, while on the other hand there are three other fossils which exactly 
correspond with our specimens, and are marked only with definite radiating striae 
of exactly the same character as in them. Under these circumstances Mr. Newton 
.came to the same conclusion as myself, that the latter as well as our English 
species ought to be referred to Sandberger's species, and regarded as in all 
probability distinct from Schlotheim's shell. It is possible that Clarke included 
both species under one head. 
Euomphalus striatus, Goldfuss,^ is another very similar shell. In it the radii 
do not seem to divaricate or increase, and the shell is less angulated and bears a 
small rounded keel. When Mr. Roberts and I examined it we came to the con- 
clusion that our shells did not belong to this species, but to Sandberger's. They 
certainly do not belong to the genus Euomphalus. 
Belleroplion radiatus, d'Orbigny,® which that author identifies with Porcellia 
retrorsa, Minister,^ has rather coarser striae, which seem to bend rather forward on 
the shoulder. The whorls also seem to be more definitely oval and increasing more 
slowly. D'Orbigny and Miinster describe it as striated for three-quarters the 
^ 1820, von Schlotheim, ' Petrefact.,' p. 65, pi. ix, figs. 2 a, b. 
2 1843, F. A. Romer, ' Verst. Harzgeb.,' p. 31, pi. viii, figs. 16 a — e. 
3 1850, P. A. Eomer, ' Beitr.,' pt. 1, p. 38, pi. v, figs. 2S a^d. 
* 1884, Clarke, ' Neues Jahrb. f. Min.,' Beil.-Band iii, p. 348. 
^ 1844, Goldfuss, ' Petref. Grerm.,' vol. iii, p. 84, pi. clxxxix, figs. 15 a — c. 
« 1840, de Perussac and d'Orbigny, ' Hist. Nat. Ceph.,' p. 216, (Bellerophon) pi. vi, figs. 20—23. 
7 1839, Miinster, ' Beitr.,' pt. 1, p. 38, pi. ii, figs. 8 a—c. 
