Pisces. | UPPER PALZOZOIC VERTEBRATA. 639 
each end, with a slight sigmoidal curve; this ridge is crossed by seven or eight large, obtusely rounded 
wrinkles, which become obsolete as they approach the thin inner margin; surface finely granuloso-punctate 
under the lens, 
This species most resembles some of the wing-shaped forms of the P. sublevis, but the whole tooth 
is more strongly contorted sigmoidally ; the external oblique margin is more thickened, ridge-like, and deflected ; 
and above all, the great size of the transverse waves or wrinkles easily distinguishes it. The length of a perfect 
specimen is one inch three lines, width of the broad posterior end nine lines, depth of the middle of the external 
margin four lines, width of the transverse wrinkles rather more than one and half line. 
Position and Locality.—Rare, from the black upper limestone of Derbyshire. 
Explanation of Figures.—P\. 3. G. fig. 10 (upper figure), natural size. 
Pacinopus FovEOLATUS (M°Coy). Pl. 3. G. fig. 11. 
fief —M°*Coy, Ann. and Mag. Nat. Hist. 2nd Series, Vol. IT. 
Desc.—Longitudinally clavate, depressed, nearly three times longer than wide; terminal end narrow, 
subtruncate ; surface obliquely crossed by nine or ten thick, flat, imbricating ridges, varying from one line 
to half a line wide; they run nearly straight, but each has got an abrupt angular bend about the middle, 
which makes the posterior half of each edge seem about half a line further out than the anterior half; 
each imbrication has one, or rarely two rows of large, equidistant puncta, or small pits. 
This differs from the P. Jonesti (Ag.) in its very narrow, elongate form, more numerous, flat, imbri- 
cating ridges, the row of notch-like curves one in the edge of each, and the regular rows of great puncta. 
The specimen described is imperfect, but seems to have been about one and quarter inch long and four lines 
wide. 
Position and Locality—From the upper black beds of carboniferous limestone in Derbyshire. 
Explanation of Figures.—Pl. 3. G. fig. 11, natural size. 
Pacitopus JonEsit (Ag. name only.) 
Ref. and Syn. = P. Jonesii + P. transversus Ag. lists; Portk. Geol. Rep. t. 14a, f. 6, 7. 
Desc.—Posterior tooth longitudinally and obliquely sub-elliptical, tumid, moderately convex; rather 
flattened towards the posterior elliptically pointed end; moderately convoluted towards the outer anterior 
corner ; one yery deep oblique concavity, about one-third the length from the anterior margin, divides the surface 
into two large oblique lobes, the anterior of which slopes gradually so as to be most prominent along the 
anterior articular margin ; the posterior one obtusely rounded, scarcely defined from the posterior edge, except 
at the posterior extremity, where it is very slightly reflected, giving an indication of the third ridge of 
Cochliodus; surface marked with subequal, very deep, longitudinal hollows ; leaving strongly marked projecting 
ridges, averaging three in the space of two lines in the middle concavity (rather more on the anterior ridge, and 
less on the posterior one); in old teeth a considerable space of the inner posterior corner is without these 
longitudinal indentations, which extend over the rest of the tooth; surface coarsely granulo-punctate ; average 
length nine lines, width of anterior margins four and half lines. 
This species is most nearly allied to the P. obliquus, but the oblique ridges are much broader and more 
obtuse, and the middle one is not separated from the posterior margin by a marked concavity. It is possible, 
nevertheless, that they may be the upper and lower teeth of the same fish; but as I have no independent 
knowledge of the dentition of the upper jaw in either Pacilodus or Cochliodus, this can only be a vague 
suggestion, founded on some general accordance of the teeth. 
Position and Locality—Not uncommon in the lower carboniferous limestone of Armagh ; very rare in the 
lower carboniferous limestone of Lowick, Northumberland. 
[FAsc. 111.] 4N 
