On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 398 
An example from the Bristol Museum (PI. L., fig. 8.) shows the position of four 
teeth in natural sequence. The inner ones are almost straight, the lateral extremity 
broadly expanded, whilst those placed externally are concavo-convex, narrow and 
laterally somewhat more pointed. 
This species is found in the bone-bed at the base of the Mountain Limestone at 
Bristol, whilst O. xamosus is found only in the black limestone above. 
Formation and locality : Mountain Limestone bone-bed, Bristol. 
Ex coll. Earl of Enniskillen ; Bristol Museum. 
Orodus porosus, M‘Coy. 
(Pl L., fig. 10.) 
Orodus porosus—M ‘Coy, 1848. “ Ann. and Mag. Nat. Hist.” 2nd Ser., Vol. IL., p. 131. 
* F, J. Pictet, 1854. “Traité de Paléont,” Vol. II., p. 264. 
3 J. Morris, 1854. “Brit. Foss.,” p. 335. 
ns . Morris & Roberts, 1862. “Quart. Journ. Geol. Soc.,” Vol. XVIII, p. 101. 
ry 3 J. J. Bigsby, 1878. ‘Thesaurus Devonico-Carb.,” p. 359. 
Teeth, ‘‘sub-cylindrical, transverse diameter (or length of base) six or seven times 
greater than the antero-posterior ; anterior and posterior margins nearly parallel, 
the middle being scarcely wider than the ends, which are obtusely subtruncate ; 
sides slightly tumid, converging to a narrow mesial ridge ; one small obtuse mesial 
cone not exceeding the short diameter of the base in height, and forming an obtuse 
ridge to the base on each ; on each side there are four or five smaller tubercles, the 
smallest towards the ends, only those nearest the centre send one or two small ridges 
down the anterior side, while the posterior is more regularly ridged: basal margin 
tuberculato-plicate ; surface coarsely punctured, except on the prominent worn points 
which are smooth; transverse diameter usually about nine lines, short diameter 
one and a half line.’ —(M‘Coy.) 
This species was described by Prof. F. M‘Coy in the “ Annals and Magazine of 
Natural History,’ without illustration, as was also Orodus compressus, M‘Coy. 
Both form a part of the collection of types presented to the Geological Society by 
the late Admiral Jones. 
Orodus porosus, M‘Coy, most nearly approaches O. elongatus, Ag., in general 
character. It may be distinguished from it, by the lateral ridges being produced 
along the upper surface of the crown, with the carina, so as to form a number of 
small secondary cones. The crown is also level and straight, whilst in O. elongatus 
it is raised in the central portion to form a wide median cone. 
Formation and locality : Mountain Limestone, Armagh. 
Ex coll. Museum of Geological Society. 
3R2 
