440 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 
Cochliodus magnus—F. J. Pictet, 1854. ‘Traité de Paléont.,” Vol. I1., p. 267. 
Helodus planus, 5) 1854. seers ULB 5 ILS fo ABM 
Cochliodus magnus—F. M‘Coy, 1855. “Brit. Paleeoz. Foss.,” p. 622. 
Helodus planus, p 1855. 3 3 »  p- 631. pl. 31, figs. 12-15. 
Psephodus magnus—L, Agassiz, 1859. “MSS. Enniskillen, Coll.,” . 
Cochliodus magnus—Morris & Roberts, 1862. “Quart. Journ. Geol. Soc.,” Vol. X VIII., p. 100. 
Psephodus magnus, 55 5 1862. 55 _ + 5 op NVI JO LLOIL, 
a 53 Enniskillen, 1869. Catal. Types, Foss. Fishes,” p. 7. 
Cochliodus magnus—Young& Armstrong, 1871. “Trans. Geol. Soc.' Glasgow,” Vol. ITT., supt. p. 70. 
Helodus planus, a a3 1871. 55 . - % by WO UN FOL A: 
Armstrong, Young, 
oO” + 
Cochliodus magnus 
=) and Robertson, 
\ 1876. “Catal. West. Scot. Foss.,” p. 61. 
Helodus planus, *. 1876. % 9% rr Td OR 
Psephodus magnus, _ r 1876. 3 35 5 fo at 
9 % J. J. Bigsby, 1878. “Thesaurus Devonico-Carb., p. 364. 
. ss L. G. de Koninck, 1878. “Fauna du Cale. Carb. d. 1. Belgique,” p. 60, pl. iv., 
figs. 14-17. 
Posterior tooth irregularly pentagonal, or sub-rhomboidal, broadly convex, 
moderately arched from side to side, and more or less inrolled at the outer or 
anterior margin ; the antero- and postero-lateral margins diverge from the anterior 
portion of the tooth; the antero-lateral margin straight or slightly concave, forms 
a sutural edge for the attachment of the median tooth ; posterior margin rounded. 
“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 obtuse slightly inrolled outer margin; anterior and 
posterior sutural edges diverging obliquely from the short outer margin ; posterior 
one longest. Anterior tooth subtrigonal, obliquely semi-elliptically pointed in front, 
and with an oblique nearly straight sutural edge, marking the posterior face of the 
triangle.” The edges of the teeth are all more or less vertically crenulated and the 
surface uniformly punctate. 
The Heloduslike teeth occupying the intermediary portion of the palate are 
“irregularly elongate, oblong with a slight oblique diagonal twist, narrowed, and 
rotundato-subtruncate at the ends, between which the crown widens ; widest nearer 
to one end than the other ; surface flattened obtusely. slightly convex”. They are 
crenulated or plicated along the edges, and the surface 1s punctate as in the teeth 
situated on the jaws. | 
The large number of teeth.comprised in this species are only roughly included 
in the above descriptions. Their forms are very complex and scarcely two are 
alike. It appears possible, however, to distinguish amongst the larger specimens 
two distinct sets, which in all probability belonged respectively to the upper and 
lower jaws. In the one the crown is semi-globose in section from front to back 
and highly convex laterally ; occasionally one or other part of the crown is worn 
or abraded by attrition to a flat surface (Pl. LV., fig. 10). In the other the teeth are 
