622 BRITISH PALA®OZOIC FOSSILS. [ Pisces. 
made to suggest this species as probably the filling up of the space between the teeth of C. contortus, in Portlock’s 
Geol. Report, p. 466, as I know that that excellent authority holds them to be well separated species; and 
further 1 might add, that it would be very unusual to find any teeth of the kind in the position indicated. 
Position and Locality.—Not very uncommon in the carboniferous limestone of Armagh. 
Explanation of Figures.—P. 3. 1. fig. 24, right posterior tooth, natural size, seen from above; fig. 24a, 
profile of same specimen seen from the outer or convoluted side ; fig. 244, transverse section of No. 24; fig. 25, 
larger and more sharply marked specimen; fig. 25, profile of last specimen (convolution of the margin con- 
cealed by the matrix) ; fig. 26, anterior tooth natural size viewed from above. 
: CocHLIODUS CONTORTUS (Ag.) 
Ref—Ag. Poiss. Foss. t. 19, f. 14. 
Desc,—Sides of jaw and lateral rows of teeth converging at an angle of about 60°; posterior tooth oblong, 
obliquely truncated on the outer side of the posterior end to form the posterior point ; the posterior edge rather 
abruptly raised to form the posterior oblique ridge behind, sloping into a rather deep, oblique hollow, which 
defines the middle oblique ridge, which is much the most prominent, and strongly rounded of the three ; anterior 
ridge coinciding with the anterior margin, very slightly raised, little tumid, separated by a moderate concavity 
from the steeply rounded side of the middle ridge, and forming an angle of 80° with the outer margin; second 
tooth narrow, its -posterior half very convex, forming a prominent, rounded ridge, rising abruptly from the 
posterior margin, but sloping sigmoidally to the anterior margin, which is not again relieved; anterior teeth un- 
known ; surface either smooth or finely granulo-punctate, by the openings of medullary canals, as in the C. acutus. 
Average length of posterior tooth one inch five lines, greatest width eight lines, width of middle tooth five lines. 
The two posterior teeth are very strongly inrolled spirally on their outer margins, especially the middle one. 
The anterior teeth are as yet unknown, but I have no doubt that they resemble those which I have described in 
C. acutus. The posterior tooth was supposed by Agassiz to be two separate teeth, supposing (from the cast) 
that the hollow between the middle and posterior ridges was a suture; this is however not the case manifestly, 
when specimens are examined. The bony jaw extends for three lines in depth below the teeth, and extends a 
little in front of the anterior ones. The species is easily distinguished from the C. acutus by the greater 
breadth, size, and obtuse rotundity of all its oblique ridges, and having the anterior ridge of the posterior tooth 
much smaller than the middle one, while it is much more prominent in that species. 
Position and Locality.— Rather rare in the carboniferous limestone of Armagh. 
CocHLIODUS MAGNUS (4g. name only). 
Ref:—Portk. Geol. Rep. t. 14a, fig. 4. 
Desc.—Posterior tooth irregularly rounded, subrhomboidal, broadly convex, and moderately arched from 
side to side, but less inrolled at the outer margin than in the other species; anterior margin broad, and 
forming an angle of about 85° with the outer margin; outer and inner margins diverging from the front for 
about half the length of the tooth, where the outer margin is abruptly bent inwards at a yery obtuse angle, 
to form the oblique posterior truncation of the genus, leaving at the angle a sort of obtuse beak-like pro- 
minence, corresponding to the middle diagonal ridge of the other species, and from whence a very ill-defined 
diagonal gibbosity extends obliquely towards the inner posterior margin, chiefly marked by the abrupt sloping 
of the surface posterior to it, while the surface in front of it slopes very gradually to the anterior suture ; 
no other diagonal ridge or sulci. Middle tooth obscurely trapezoidal, having a broad, moderately convex inner 
margin, from whence the surface is uniformly and gently arched towards the opposite very short side, or ob- 
tuse, slightly-inrolled outer margin; anterior and posterior sutural edges diverging obliquely from the short 
outer margin; posterior one longest ; anterior tooth subtrigonal, obliquely semielliptically pointed in front, and 
with an oblique nearly straight sutural edge marking the posterior face of the triangle. Surface uniformly and 
evenly conyex ; surface of all the teeth with a slightly smaller porosity than the C. contortus; the edges of 
