CTETOCERATIBiB. 
299 
were confounded with it, and this was placed with 0. ibex. Now 
that nearly complete straight shells of the latter have been seen, it 
is known never to he curved. The ribs too and the circular form of 
the present species ought easily to separate it. Again, it is similar 
to the curved shells which may be true Lituites, hut is more robust, 
and the specimens figured prove it to have a quite different aperture. 
It is indeed a Cyrtoceras, which none of the others are, and it 
appears to he not an unusual thing, to judge by Barrande’s figures, 
for Cyrtocerata of this ribbed and mediogastric group to contract in 
the body-chamber. The present species is very like several figured 
by that author^ but has coarser ribs than any.” {BlaTce.) 
Horizon. Wenlock. 
Locality. Dudley, Worcestershire. 
Eepresented in the Collection by a single example. 
Cyrtoceras (Meloceras) cognatum, Barrande, sp. 
1867. Cyrtoceras cognatum, Barrande, Syst. Sil. de la Boheme, vol. ii. 
pt. i. p. 633, pi. cxcix. If. 3o-45. 
Sp. Char. Shell strongly curved. Upon a chord of 38 millim., 
subtending the concav.e side, the highest perpendicular is 8 millim. 
The transverse section is circular. The increase in the septate 
part is in the ratio of 1 : 2, in a length of 25 millim. The body- 
chamber is moderately developed, and occupies about ^ of the 
total length of the shell. The plane of the aperture is inclined 
towards the convex side. The distance between the septa does not 
exceed ^ the diameter of the shell. The siphuncle is about midway 
between the centre and the convex border ; its elements are 
cylindrical. The surface of the shell is ornamented with very 
prominent transverse annulations about line distant from each 
other where the diameter of the shell is 5 lines. These annu- 
lations form a sinus upon the convex border, and the sutures of the 
septa lie between them. The surface of the test is ornamented 
with a network of fine, close-set, transverse strise which are crossed 
by widely-spaced longitudinal striae. These ornaments are scarcely 
visible to the unaided eye. The transverse striae number from 
8 to 10 between 2 annulations measured from summit to summit. 
Eemarl's. The nearest ally of this species is 21. pergraium, Barr., 
sp. {infra), but the form of the latter is much less arcuate, and its 
longitudinal striae are but little developed beyond the septate part 
^ See Barrande, Sjst. Sil. de la Boheme, vol. ii. pt. i., plates cxcviii., cxcix. 
