On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 439 
The teeth included. in this genus were originally named by Prof. Agassiz, Coch- 
liodus magnus and they have since been figured by Portlock (Geol. Rept. pl. 14a, 
fig. 4) and described by Prof. M‘Coy (Brit. Paleeoz. Foss., p. 622). Admiral Jones, to 
whom ichthyologists are indebted for much research and many valuable suggestions 
in connection with the fish remains of the Mountain Limestone, indicates a proba- 
bility that the teeth of Cochhodus magnus and Helodus planus belonged to the same 
fish. He does not, however, suggest any possible arrangement of the palates. 
The inference is very likely correct, and if a tolerably perfect example of the palate 
should fortunately be discovered, it will probably be found to consist of three 
teeth of the species hitherto known as Cochliodus magnus on each ramus of the jaws, 
increasing in size backwards, and a number of teeth of Helodus plaxus arranged 
between the jaws, forming a close pavement-like series also increasing in size 
backwards. 
During the year 1858, Prof. Agassiz removed this group of teeth from the 
genus Cochliodus and instituted the newgenus Psephodus for its accommodation. The 
so-named types remained in the collection of Lord Enniskillen but like many others 
were not described. 
In the Paleontology of Illinois (Vol. IL., p. 92) Messrs. Newberry and Worthen 
describe and give figures of a number of palates from which they have originated 
the genus Aspidodus. At the same time they indicate its relationship to the teeth 
of Cochliodus maynus, Ag., and Helodus planus, Ag., and suggest the latter should 
be included in their new genus. There is little doubt that they are generically 
identical and should be joined together in one genus, but as priority is generally 
taken as the guide in instances of synonymic nomenclature, it will be evident that 
A gassiz’s genus Psephodus must be retained and the genus Aspidodus, Newberry 
and Worthen, merged with it. 
Psephodus magnus, Agass., MSS. 
(Pl. LV., figs. 1-14.) 
Cochliodusgmagnus—L. Agassiz, 1838. “Rech. sur 1. Poiss. Foss.” Vol. IIT., pp. 174, 384 (indet). 
Helodus planus, 1838. » » » LL,p. 178. 
Cochliodus"magnus—J, E. Portlock, 1843. “Rept. Geol. Londonderry, &c.,” p. 466, pl. XTVa, fig. 4 
Helodus planus, — - 1843. are 55 9 », 462. 
Cochliodus magnus—C. G. Giebel, 1848. “Fauna der Vorwelt,” Vol. I., pt. 3, p. 336. 
Helodus planus, 58 1848. Bs ‘ e » L., pt. 3, p. 341 
Cochliodus:magnus—-H. G. Bronn, 1848. “Nomencl. Palont.,” p. 317. 
Helodus planus, 5 1848. . . p- 583. 
Cochliodus magnus, , 1849. “Enumerator Paleont.,” p. 647. 
Helodus planus, 1849. % " p- 647. 
Cochliodus’magnus—J. Morris, 1854. “Catal. Brit. Foss.,” p. 322 
Helodus planus, 5 1854. 55 5 a [Dh GAS 
TRANS, ROY, DUB. SOC., N.S., VOL. I. 3 Z 
