314 
IfAITTILOIDEA. 
seen by the external cast. The appearances presented are rather 
contradictory. In the part preserved the septa appear to be | the 
diameter apart, bnt on the external cast there are lines which are 
twice as close : these may be interpreted either as ribs or septa. 
The apparent remoteness of the latter on the npper part would lead 
to the former, bnt another specimen suggests the latter interpreta- 
tion. The convexity is moderate, and the siphuncle minute and 
external.” 
This is Prof. Blake’s description of the type-specimen contained 
in the Museum of the Geological Society. The specimen preserved 
in the National Collection (figured by Blake, loc. at.) is referred by 
him with some hesitation to Sowerby’s species ; he thus describes 
it : — “ A better preserved example, apparently referable to this 
[Ooc. aj?j)roximatum']., shows a section with equal axes, but scarcely 
circular ; the increase is greater on approaching the inflated body- 
chamber, which is j its basal diameter in length, and the aperture 
has a simple circular outline. The curvature is almost lost. The 
septa in this are certainly ^ the diameter apart, but no siphuncle 
can be found on the conically-shaped septal surface. 
“ The nearest species to this in shape is Ortlioceras fretinn, but 
there is no sign of curvature in that, and the body- chamber is 
different.” 
Horizon. Wenlock Limestone. 
Locality. Dudley, Worcestershire. 
Bepresented in the Collection by the specimen figured by Prof. 
Blake in his work above cited. 
Cyrtoceras (Ooceras) acinaces, Barrande, sp. 
1867. Cyrtoceras acinaceSy Barrande, Syst. Sil. de la Boheiue, vol. ii. 
pt. i. p. 476, pi. cxviii. fif. 9-14, pi. exxiv. if. 16-18. 
Sp. Char. Shell very strongly curved, especially in the apical 
portion. Upon a chord of 120 millim., subtending the concave side 
of a specimen wanting the apical part, the highest perpendicular 
is 32 millim. The transverse section is oval, of which the small 
end corresponds with the convex side of the shell. The ventro- 
dorsal is to the convex axis as 5 : 4. The rate of increase is very 
gradual. The body-chamber is short, and occupies scarcely ^ of the 
total length of the shell. The length of the body-chamber is in some 
specimens exactly equal to the diameter of the aperture (Barrande, 
pi. cxviii. f. 9). The septa are exceedingly numerous, being about 
■J of the ventro- dorsal diameter distant from each other ; they arch 
sharply forward on the convex border of the shell, and forma 
