ORTHOCEEATID.IS. 
79 
ORDOTICIA^7 SPECIES. 
Orthoceras Avelinii, Salter. 
1866. Orthoceras AveUnii, Salter, Memoirs of the Geol. Siirv. vol. iii. 
p. 356, pi. xi. B. f. 18. 
1872. Orthoceras AveUnii, Salter, in Murchison’s ‘ Siliiria,’ 5th edition, 
p. 48, Foss. (9), f. 4. 
1875. Orthoceras Caereesiense, Hicks, Quart. Journ. Geol. Soc. vol. 
xxxi. p. 189, pi. xi. ff*. 8-10. 
1882. Orthoceras AveUnii, Blake, British Foss. Ceph.pt. i. p. 131, pi. vi. 
ff. 1, 2. 
-S/9. Char. Shell straight. Section elliptical, the diameters being in 
the ratio of 8 to 7. Rate of increase 1 in 7. The ornaments in the 
young shell consist of “ undulating rounded elevations, rising on the 
side of the siphuncle.” The finer ornaments are upward imbri- 
cations, about 30 in the diameter of the shell, or from 4 to 8 per 
line, but rather irregular ; tliey are a little oblique. The septa are 
parallel to them but somewhat undulating, ^ the diameter apart, 
corresponding, perhaps, to the elevations. The siphuncle is | across 
the diameter on the side to which the septa rise. (Blake.) Body- 
chamber unknown. 
Bemarks. 0. Caereesiense, Hicks, is evidently only a crushed and 
flattened form of this species, as observed by Prof. Blake. 
Horizon. Lower Llandeilo. 
Locality. Cefn Gwynlle Mine, Shelve, Shropshire. 
Fairly well represented in the Collection by specimens presented 
by J. E. Lee, Esq., F.S.A., F.G.S. 
Orthoceras audax, Salter. 
1866. Orthoceras audax, Salter, Memoirs of the Geol. Siirv. vol. iii. 
p. 357, pi. xxiv. f. 7. 
1882. Orthoceras audax, Blake, British Foss. Ceph. pt. i. p. 143, pi. xii. 
f. 8. 
Sp. Char. Shell straight. Section nearly circular, but the 
diameters are always unequal. Rate of increase 1 in 5 to 1 in 7. 
Body-chamber unknown. Septa very slightly convex, undulating 
to the extent of 3|°, being highest on the narrow side ; from J to 
1 the diameter apart. Siphuncle very slightly eccentric on the long 
axis towards that side to which the septa rise. (Blake.) 
Eemarks. Prof. Blake observes that “ it seems very probable that 
