GOilPHOCEEATID^. 
215 
shell under the name of Phragmoceras rectiseptatum, of which only 
the septate part of the shell (with the siphuncle) is known, neither 
body-chamber nor test being preserved. There is therefore nothing 
to show that this species has any affinities with the present genus. 
Blake has more recently described a species under the name of 
Phragmoceras prius, from the Bala Beds of Rhiwlas, Bala. The 
type specimen of this species is contained in the Museum of Prac- 
tical Geology ; and I am indebted to the kindness of Mr. E. T. 
Newton, E.G.S., for the opportunity of thoroughly examining it. 
The specimen is a cast of the body-chamber with several of the 
septa attached. The surface is much worn and pitted, and a small 
mass of rock almost entirely covers the region of the aperture, so 
that the latter cannot with any degree of certainty be made out. 
There is an obscure groove of a rudely rounded form in the situa- 
tion in which in an endogastric form of Gomplioceras the larger 
apertural orifice would be found, and this is the only character from 
which the generic affinities of the fossil might be deduced. It ap- 
pears to me therefore that conclusive evidence is yet wanting of the 
occurrence of the present genus heJoiu the Silurian. Ahove^ that is 
to say in the Devonian, the following species have been described, 
viz.: — Phragmoceras Brateri, Miinst. \ Orthoceratites {Gompho- 
ceras2) subfusiformis, Miinst. 0.(G.?) suhpyriformis, Miinst. 
G. sulcatulum, Murch., de Yern., and de Keyserl.* In none of 
these species does the aperture appear to be known, hence their 
affinities can only be conjectured. Their general form, however, 
would lead to the supposition that they belong to the genus Poterio- 
ceras. The species named by Saemann Apioceras olla has been 
taken by Hyatt as the type of his new genus Acleistoceras ® (Earn. 
Gomphoceratidae) ; and Phragmoceratites suhventricosus, d’Archiac 
and de Yern., is placed by Hyatt in his genus Ooceras (Earn. 
Cyrtoceratidae). The Carboniferous species (such as Orthoceras 
fusiforme, Sow., 0. cor diforme, Sow. hitherto referred to 
Gomplioceras (or to Phragmoceras) will now fall into Poterioceras. 
The genus Gomplioceras may thus be regarded, according to our 
present knowledge of it, as restricted to the Silurian epoch. 
1 Beitrage zur Petrefactenkuncle, Heft iii. 1840, p. 105, Taf. i. ff. 10, a, 6, c. 
2 Loe. cit. p. 103, Taf. xx. ff. 6, 7. 
3 Log. cit. p. 103, Taf. xx. f. 10. 
4 Geol. de la Eussie d’Europe, vol. ii. Paleont. p. 357, pi. xxv. f. 6. 
5 Log. cit. p. 277. 
6 Min. Conch, vol. iii. tab. ccxlvii., vol. vi. tab. dlxxxviii. f. 1 (not f. 2). 
