PHANEROPLEURON ANDERSONI 469 
Museum, and in another specimen marked 26117 in the same - 
collection. 
Their length exceeds the greatest vertical diameter of the body. 
A taper central lobe extends through the whole length of the fin, end- 
ing in a point at its fine end. It is covered throughout with cycloid 
scales, having the same characters as those of the body, and both edges 
are fringed with delicate fin-rays. 
The notochord was persistent throughout the whole length of the 
vertebral column, while the superior and inferior arches were well 
developed and thoroughly ossified. 
The neural spines are long, and are curved, so as to be somewhat 
concave forwards and upwards. In the posterior moiety of the body, 
elongated interspinous bones, narrow in the middle and expanded at 
the ends, are adapted to them. These interspinous bones increase in 
length from before backwards to beyond the middle of the dorsal fin, 
and support the fin-rays whose bases are broad and solid, while they 
divide into a series of branchlets at their ends. There may be more 
than one fin-ray to each interspinous bone. 
The dorsal fin, commencing with the posterior half of the body, 
gradually increases in height posteriorly, as its upper margin remains 
parallel with the axis of the body, while the dorsal line of the body 
converges towards that axis; the fin terminates posteriorly in an al- 
most vertically truncated extremity. 
The ribs attain a considerable length, even close to the head, and 
are continued through the whole length of the abdomen, passing 
gradually into the subcaudal bones. They are well ossified, and hence, 
in the fossil state, they stare through the thin integumentary scales of 
the fish so as to suggest its generic name. 
The anal fin is somewhat lanceolate in shape, inclined downwards 
and backwards, and so long that its lower extremity is as distant from 
the axis of the body as the upper edge of the dorsal. It is supported 
by interspinous bones like those of the dorsal fin. 
The inferior lobe of the caudal fin commences immediately behind 
the anal, and its rays appear to be supported by similar interspinous 
bones, at least anteriorly. It can be traced backwards to near the 
extreme end of the body. The superior lobe, on the other hand, seems 
to have been obsolete. 
