On the Fossil Fishes of the Carboniterous Limestone Series of Great Britain, 367 
are eleven rows of tubercles on one side. The walls of the spine are thin and it 
appears to be owing to this that they are so much compressed. The diameter between 
the sides is little more than one-fourth that between the anteriorand posterior margins. 
The anterior margin is formed by a strong carina of shining ganoine, ‘1 of an inch 
across. The posterior one is not well defined but appears to have been devoid of 
denticulations. 
Another specimen exhibits the extremity of the longer branch of the spine, an 
impression is preserved a little over two inches long, the extremity is well preserved 
and exhibits somewhat similar peculiarities to that of C. paradoxa, Agass. The 
diameter of the stem of the spine taken from the impression on the matrix is ‘4 of 
an inch : half an inch from the extremity the spine becomes suddenly expanded to 
‘9 of an inch. At its distal end it is divided into four toe-like prolongations, each 
of which is covered by asingle large plate of ganoine, oval in form and :2 of an inch 
across the longer diameter. The body of the spine was coated with enamelled plates 
of unequal size averaging ‘1 of an inch across, and without definite arrangement. 
This species is distinguished from Cladacanthus paradoxus by its much larger 
size. 
Locality : Mountain Limestone of Armagh. 
Ez coll, Earl of Enniskillen, 
Genus.—Physonemus, Agass. MS. 
Physonemus—Agassiz, L., 1833. “ Poiss. Foss.,” p, 176, MSS. 
99 M‘Coy, F., 1855. “ Brit. Palzeoz. Foss.,” p. 638. 
** Fin spine, much compressed, with a variable backward curvature ; base of inser- 
tion large ; posterior edge with two rows of small denticles. Surface covered with 
very numerous cord-like longitudinal ridges, which swell at short regular intervals 
into small bubble-like tubercles.” —(M‘Coy). 
Professor Agassiz named the spines of this genus. Professor M‘Coy formulated 
the description, from which the above is taken. | 
Physonemus arcuatus, M‘Coy. 
(EESXe VALI ios 83) 
Physonemus arcuatus—F. M‘Coy, 1848. “Ann. & Mag. Nat. Hist.,” 2nd ser., Vol, IT. Deplelyie 
” of J. Morris, 1854. “Catal. Brit. Foss.,” p. 338, 
” » F. J. Pictet, 1854, ‘Traité de Paléont.,” Vol, II., p. 291. 
9p % F. M‘Coy, 1855, “ Brit. Paleeoz. Foss.,” p. 638, pl. 3 I., fig. 29, 
5 Morris and Roberts, 1862. ‘ Quart. Journ. Geol, Soe.,” Vol. XVIIL ,p. 101. 
30 5 J. J. Bigsby, 1878. ‘Thesaurus-Devonico.—Carb.,” p. 363, 
i Spine, slightly imperfect at the distal extremity, probably half an inch missing 
—remaining portion 5:5 inches in length along the convex surface. Two-thirds ne 
length of the spine was exposed, the remaining third was embedded in the bedy 
TRANS, ROY. DUB. SOC., N.S, VOL. I, 30 
