On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain, 369 
This species, like many others, was named by Prof. Agassiz but left undescribed. 
A specimen, which very doubtfully belongs to this genus, is figured in M‘Coy’s 
“ Brit. Paleeoz. Foss.,” p. 638, pl. 3 I, fig. 30. It is described as “a fragment five lines 
long, straight, without perceptible tapering, one and a half lines wide, about four 
ridges in the space of one line ; the intervening spaces being rather wider than the 
ridges themselves, which swell at alternate intervals into oval, smooth tubercles, 
about their own diameter apart: intervening spaces with about three longitudinal 
punctured strize. The species is easily distinguished from the P. arcuatus by its 
small dimensions, slender tapering form, and straightness ; two small rows of teeth 
on the posterior side.” 
The original specimen, named by Prof. Agassiz, Physonemus subteres, is in the 
Jones’ collection at the Geological Society. It is 20 inches in length and less than a 
quarter of an inch in diameter. The specimen is imperfect at each end, and the 
portion preserved is in great part embedded in the matrix. The sides are covered 
with a series of longitudinal ridges with intermediate hollows about the same 
diameter as the ridges. The latter are coated with enamel and are, at intervals, 
slightly produced so as to form a bead-like irregularity of the surface. The pos- 
terior surface, which is in part exposed, is hollowed into a longitudinal groove. The 
angle formed by the side and back of the spine is devoid of denticulations. 
The specimen does not present the characteristic features of the genus Physonemus 
as defined above. It has far more the appearance of a Ctenacanthus, but in default 
of better preserved examples it is perhaps premature to remove it to that genus. 
It may have been a portion of a long spine like the one figured of P. attenwatus. 
Formation and locality : Mountain Limestone, Armagh. 
Ex, coll. Geological Society, London. 
Physonemus attenuatus, Davis. 
(Pl. XLVIL,, fig. 10.) 
Spine, broad and strong near the base, rapidly tapering and acuminate towards 
the superior extremity. Jt is six inches in length along the outer curvature. The 
exposed portion of the spine is imperfect, and in great part broken away. The 
surface was striated longitudinally. The base gradually expanding downwards is 
widest at the extremity being 1:3 inches, and apparently produced on its posterior 
surface to form an acute angle, this appearance however, may be due to imper- 
fection in its preservation. The internal cavity is large near the base of the spine 
but becomes very small towards the point, and terminates before reaching it. 
This species is very distinct from any hitherto described. Its long attenuated 
form, and the peculiar expansion of the basal region renders its deterraination 
easy: 
- Formation and locality ; Mountain Limestone, Armagh. 
Ex coll. Earl of Enniskillen. 
302 
