On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 391 
Teeth, large, powerful, massive: transverse diameter about three times that of 
the antero-posterior one: median surface of crown broad, narrowing laterally to 
two-thirds its diameter ; lateral terminations bluntly subtruncated. Median cone 
prominent, with an acutely-angular antero-posterior ridge, on each side a median 
carina somewhat sinuously descends to the lateral extremities, with divaricating 
anterior and posterior ridges, the latter occasionally bifurcating into two or more 
branches as they approach the margins. The carina and ridges in unworn specimens 
are sharp and well defined, separated by deep and wide concave furrows. Surface 
uniformly punctate. Base of crown irregularly concave. Root, very large, about 
four times the depth of the crown, coarsely fibrous or spongy, full of lacunal 
interstices. Anterior surface slightly convex, deeper than posterior which is 
concave: base joins the two diagonally having nearly the same antero-posterior 
diameter as the crown. Dimensions of a large example, transverse diameter four 
inches, antero-posterior diameter 1°2 inches ; thickness of crown :2 to °4 of an inch ; 
depth of base 1:1 inches. 
The teeth of Orodus ramosus exhibit considerable variety in form as well as 
surface ornamentation. In one of the largest examples Pl. L., fig. 2, the number 
of bifurcating branches from the median lateral carina is very large and intricate. In 
the same specimen the surface of the crown is so close in texture that only a very 
slight trace of the punctuation is visible, though in other specimens of equal size 
it is very easily perceptible. The series of three large teeth represented in PI. L., 
fig. 1, from the Bristol Museum, appear to be much worn, both the median cone and 
the lateral carina and ridges are almost obliterated. The specimen Pl. L., fig. 1, 
as well as the one represented by Pl. L., fig. 3, from the collection of Lord 
Enniskillen, are interesting because they exhibit the relative position occupied by 
the teeth in the mouth, the central cones in each case being contiguous, whilst 
the lateral extensions are separated. 
Professor Agassiz expresses a doubt as to whether the teeth of O. ramosus, and 
O. cinctus, may not have belonged to one species. Professor L. G. de Koninck 
appears also to consider that the two should be united (“ Fauna du Cale. Carbonif. 
de la Belgique”). After a very careful examination of all the material available, how- 
ever, it appears probable that the determinations made by Professor Agassiz in the 
first instance are correct. The small specimens of O. ramosus are as distinctly ridged 
as the larger ones (see Pl. L., figs. 6, 7), and throughout appear to possess the same 
characters, whilst the smooth rounded forms of O. cinctus are equally persistent. 
The teeth of Orodus ramosus, Agass., have been most commonly found at Bristol 
in the black limestone. Specimens have also been obtained at Oreton, in Shrop- 
shire, and a single specimen from Armagh exists in the collection given by the late 
Admiral Jones to the Geological Society. The latter presents some features 
differing from the Bristol specimens. Its transverse diameter is greater in propor- 
tion to the antero-posterior one, and it is laterally much more attenuated. The 
TRANS, ROY. DUB. SOC, N.S., VOL. I. mle 
