On the Fossil Fishes of the Carboniferous Limestone Serves of Great Britain. 395 
attenuated in proportion to its length, the secondary lateral ridges are more regular 
and symmetrical in arrangement. 
Formation and locality : Mountain Limestone, Armagh. 
Ex. coll. Museum of Geological Society, London ; Earl of Enniskillen. 
Orodus angustus, Agass. (MSS.) 
(Pl. LI., fig. 4.) 
Orodus angustus—L. Agassiz, “ MSS., Capt. Jones’ Collection Geol. Soc., London.” 
5 5 J. E. Portlock, 1843. ‘ Report Geol. Londonderry, &c.,” p. 461. 
ms 33 J. Morris, 1854. “Cat. Brit. Foss.,” p. 335. 
ss S Morris and Roberts 1862. “ Quart. Journ, Geol. Soc.,” Vol. XVIIL., p. 101. 
o 2p J. J. Bigsby, 1878. “ Thesaurus Devonico-Carb.,” p. 359. 
Teeth, medium size, uniformly narrow, transverse diameter 1:1 inch, width of 
central cone ‘15 of an inch, laterally slightly less; lateral terminations rounded, 
median elevation slight with an antero-posterior ridge, no lateral carina, numerous 
ridges parallel with the median one, antero-posterior section circular, base of crown 
contracted, surface uniformly punctate. Root shghtly deeper than the height of 
the crown, concavo-convex, base concave, corresponding to the convexity of the 
crown, coarsely porous in structure. 
This species, along with O. elongatus, O. gibbus, and O. catenatus, were named 
in Manuscript, by the late Prof. Agassiz from three specimens in the collection of 
the late Admiral Jones. The types so named were presented to the Geological 
Society, London, by Admiral Jones, and form the subjects ofthe present descriptions, 
along with others selected from the collection of Lord Enniskillen. 
The teeth of Orodus angustus, Ag., may be distinguished from those of O. elongatus, 
Ag., by the absence of a lateral keel or carina, the more uniform diameter of the 
tooth antero-posteriorly, the almost entire absence of a central cone and the 
irregular arrangement of the ridges on each side. Similar characters also separate 
it from O. porosus, M‘Coy. 
Formation and locality : Mountain Limestone, Armagh. 
Ex, coll. Earl of Enniskillen ; Museum, Geological Society. 
Orodus catenatus, Agass. (MSS.) 
(Pl. LE, figs. 5, 5a.) 
Orodus catenatus—L. Agassiz, “MSS., Capt. Jones’ Collection, Geol. Soc., London.” 
5 5 Portlock, 1843, “ Report Geol., Londonderry, &e.,” p. 461. 
. 56 Morris and Roberts, 1862. “ Quart. Journ. Geol. Soc.,” Vol. XVIII., p. 101. 
3 5 J. J. Bigsby, 1878. ‘Thesaurus Devonico-Carb.,” p. 359, 
Teeth, small, 35 of an inch in transverse diameter. Crown rises from each 
lateral extremity with uniform gradation to the median cone. The latter is 
prominent, round ; apex smooth, probably from wear. Median ridge extends from 
central cone along each lateral extension. From the median ridge secondary ones 
