LLANVIRN BEDS, ABEREIDDY, PEMBROKESHIRE. 637 
superposed chevrons, which is situated mesially in ‘thts pan of the 
fossil. The intervals between the septa vary from + to § inch, and 
the greatest width of the chevron-band is ? inch. 
On removing the shell from its mould, the chevron-band appears 
to be somewhat distorted anteriorly, and is then CoD forward 
as a narrow groove, partly disconnected and about § inch wide, to 
the anterior margin of the fossil. On the shell itself there is a 
ridge corresponding to the above-mentioned groove, and when this 
ridge is cut open, it is seen to be filled with material differing 
somewhat from the rock in which the fossil is imbedded. This 
may, possibly, be the siphuncle, and, as already stated, the groove 
corresponding to it is apparently continuous with the chevron-band. 
The anterior portion of the fossil is, however, in such a bad state of 
preservation that but little can be made of it; the septa are not 
seen here; but some irregular coarse corrugations are present, 
running round the part of the shell which is preserved, and roughly 
corresponding to its lines of growth. The corrugations may repre- 
sent an ornamentation on the external surface of the shell. On 
some parts of the shell small irregular ridges can be seen; but it 
is doubtful whether these represent original structure or not. The 
doubt that occurs on this point is due to the fact that the cleavage 
so nearly coincides with the bedding that it is possible some of 
these crumplings may be due to the cropping-out of the cleavage- 
planes along the plane in which the fossil hes. 
No part of the body-chamber appears to be preserved in our spe- 
cimen, because if the ridge on the shell, already described, represents 
the siphuncle, then the body-chamber ‘aust lie beyond it. 
Five species of Conoceras (Bathmoceras) have been described :— 
Conoceras eoum (Blake) * from the Arenig of the Shelve. 
angulosum +, Bronn, from Lake Huron, America. 
Bathmoceras complecum, Barr. t : 
: from D, d, 1. Wosek, Bohemia. 
preposterum, Barr. ph Te Wilowels sglneuivi, 
— Linnarsoni, Angelin §, from Kinnekulle, Westrogotiia, Sweden. 
In 1874, Kayser|| described, from the Devonian of Bicken, near 
Herborn, in Nassau, a fossil which he referred to Gomphoceras ; it 
consists of a longitudinal section of a portion of.the body-chamber, 
together with 15 segments immediately adjoining it. All the 
sutures of the septa in the chambered portion are peculiar, in that 
they bend backward, forming funnel-shaped depressions; but this 
bending is most marked in the last 11 septa. There is also a longi- 
tudinal groove uniting the apices of these depressions. 
Kayser figures a surface-view of one of the septa from the middle 
of the fossil, showing (1) what he supposes to be a siphuncle placed 
* Blake, Brit. Foss. Ceph. part i. p. 165, pl. xvi. fig. 5. 
+ Trans. Geol. Soc. 2nd series, vol. i. pl. 26. fig. 6; Bronn, Leth. Geogn. 
vol. 1. p. 98, pl. i. fig. 7. 
{ Barrande, Sil. Syst. de la Bohéme, vol. 11. texte ui. pp. 797 & 799. 
§ Angelin and Lindstr om, Fragmenta Silurica, p. 8, pl. xvi. fig. 4. 
|| Zeitschrift der deutschen geologischen Gesellschaft, vol, xxvi. p. 671, ee 16. 
figs. 1-4. 
