[maTTHEw] A NEW GENUS AND A NEW SPECIES OF SILURIAN FISH 9 
A curious similitude to the crustacean test appears in this little 
fossil. In all the Devonian fish plates that I have seen, the tubercle 
or ornamentation is confined to the outer surface of the plate, being 
chased upon its outer layer. But in Ctenopleuron the inside (of some 
of the plates at least) is marked by distinct pits, which correspond to 
the tubercles of the outer surface. This is a common feature in the 
tests of trilobites. e.g.,Triarthrus Becki. 
If we should seek for a relative to this ancient vertebrate, tha 
genus Phaneropleuron seems to be that which comes nearest in struc- 
ture. This genus is best known by the species P. Andersoni, described 
by Huxley from the Old Red Sandstone of Dura Den in Scotland, and 
by the species P. curtum from the Upper Devonian of Scaumenac Bay, 
P.Q., described by J. F. Whiteaves. Both of these species, however, 
had an equally balanced display of fin-rays on the posterior part of the 
body, and did not have the great development of the anal fin which 
our species exhibits. Both species of Phaneropleuron also show a back 
bone passing along the centre of the body, whereas Ctenopleuron, 
(unless the imperfection of the fossil is misleading) had a back 
bone much closer to the dorsal side of the body. With only one 
specimen to depend upon and that no doubt to some extent dis- 
torted, the author does not feel satisfied that this anomalous position 
of the back bone was the natural one in the living fish, and it is quite 
possible that additional material will make necessary a modificatioa 
of the description in this respect. 
Of the ichthye nature of the fossil, however, I think there can be 
no doubt, and it is of special interest to the naturalist as it carries back 
the geological history of this type of fish to about the age of the Clinton 
group, and it is therefore one of the oldest known of fishes. 
In the West of America, Director Walcott of the U. S. Geological 
Survey, found Devonian fishes of the better known types in association 
with corals characteristic of the Niagara group; this gives countenance 
to the present discovery of fishes of a type related to Phaneropleuron of 
the Upper Devonian occurring in strata which are of Silurian age, and 
probably about the horizon of the Clinton group. 
Horizon and Locality— In connection with the description of 
Diplaspis Acadica,’ reasons are given (and they apply equally to this 
species) for supposing the strata in which it occurs, to be of about the 
age of the Clinton group. 
The locality is Cunningham Brook, near Nerepis Station, Kings 
Co., N.B., Canada. 
?Trans. Roy. Soc. Can., ist Ser., vol. vi (4) p. 49. PI. iv. 
