434 
Proceedings of the Royal Society 
which the principal ones are, as in Pygojoterus and Oxygnathus, 
unarticulated till towards their terminations. The ventrals are not 
well exhibited in any of the specimens, though in two cases portions 
of them are seen ; they seem to have been small, with delicate rays, 
whose transverse articulations are rather distant. The dorsal and 
anal fins are moderate, the former being placed far hack, and arising 
only slightly in front of the anal. Both are acuminate, triangular, 
with considerable concave posterior margins. The base of the anal 
is slightly more extended than that of the dorsal, and a well-marked 
interval occurs between its termination and the commencement of 
the caudal, It is not possible to ascertain the number of rays in 
those fins. They are rather delicate, and with their transverse 
joints about twice as long as broad — at least, in the longer rays 
before bifurcation. When the rays are in situ their articulations 
appear proportionally still more distant, owing to the usual imbrica- 
tion of the demi-rays. The anterior rays of the lower lobe of the 
caudal are stouter than those of the rest of the fin, and have their 
transverse articulations closer, the joints appearing nearly square as 
seen from the outside; as the lower lobe passes into the upper one 
the rays become more delicate, and their articulations more distant. 
The outer surfaces of the rays of the pectoral are nowhere seen, but 
in the other fins the rays are ganoid externally, and mostly smooth, 
though showing here and there, especially towards their proximal 
.... c* i • . i* rrri p i „ 
1 
extremities, traces of longitudinal striation. The fulcra are small, 
though very distinctly visible under an ordinary lens. 
Geological Position and Localities. — The specimens which I have 
included under the foregoing description are all from the Calciferous 
Sandstone series of Midlothian, in which the species seems to be 
widely distributed, though not very abundant as regards number of 
specimens. It occurs in the Wardie shales, at Wardie (Museum of 
Science and Art and collection of the author) ; near Slateford (col- 
lection of the Geological Survey of Scotland) ; near Juniper Green 
(Mr John Henderson) ; in the horizon of the Burdiehouse lime- 
stone, at Burdiehouse and at South Queensferry. Its occurrence 
in strata of similar age in Fifeshire is extremely probable, though 
the specimen from Burntisland, figured as Palceoniscus ornatissimus 
by Agassiz, seems now to be unfortunately lost. 
