436 
Proceedings of the Royal Society 
ending in the dc-nticulations of the posterior margin ; in many cases 
they are interrupted before reaching that margin, and are replaced 
by other shorter ones springing np between them. In some cases, 
also, a few of the ridges of the upper half, near the anterior- 
superior angle of the scale, likewise impinge upon the diagonal, 
consequently meeting those of the lower half at acute angles. 
The pectoral fin is well displayed in specimen Ho. 1, in which it 
measures rather more than 1 inch in length. It is of considerable 
expanse, and consists of at least 30 rays, of which the stronger ones, 
the first 15 counting from the lateral margin, are unarticulated till 
towards their terminations, where bifurcation sets in. The ventrals 
are not shown. Portion of the dorsal is seen in Ho. 1, in which it 
seems to arise opposite the anterior part of the anal, and its entire 
contour is exhibited in Ho. 3. It is triangular and acuminate, very 
high in front ; its rays, which cannot be counted, are rather deli- 
cate, and their transverse articulations considerably distant. In 
Ho. 1 the anal is seen to be of large size, and of the same triangular 
acuminate form as the dorsal. Its base is l-^ inch in extent, and 
its longer anterior rays seem to have exceeded that measurement, 
though they are cut off at the apex ; the fin is, moreover, badly pre- 
served, and its anterior margin somewhat distorted and injured. In 
the same specimen the origin of the lower lobe of the caudal is also 
shown, consisting of exceedingly closely set deeply imbricating rays, 
of which I count at least 40 up to where they begin to pass into those 
of the upper lobe, but here the tail is unfortunately truncated by 
the edge of the nodule. Interspinous bones of great strength are 
seen supporting this part of the caudal fin. 
Remarks. — This is a most distinctly-marked species, differing 
obviously from R. ornatissimus in the proportions and sculpture of 
the scales, and in the large size of the fins. I know of no other 
species with which it can at all be confounded. The first time I 
saw the most perfect of the three specimens described above, I was 
struck with the general resemblance which it bore to the Permian 
genus Pygopterus, but the larger proportional size of the scales, and 
the anal fin not being prolonged backwards, indicate that its place 
is in Rhadiniclitliys. 
Geological Position and Locality. — In ironstone nodules from the 
shales of Wardie, near Edinburgh, belonging to the Calciferous 
Sandstone series. 
