534 Prof. R. H. Tmquair — On a neio Carboniferous Fish. 



remarked, a slight upward curvature of tlie axis of the body at its 

 caudal extremity. This curvature is not seen in Eig. 2, as the 

 specimen has undergone a slight distortion, but it may be observed 

 in Fig. 1, and is still better seen in specimen No. 5, not figured. 



The rays of the median fins are very fine, frequently bifurcating 

 near their tips, and spring in bundles, vphich may be best studied in 

 the dorso-caudal. They have, in fact, the same structure as in 

 P/«. Andersoni. Each bundle results from the division, into nume- 

 rous raylets, of the distally-directed apex of a small triangular basal 

 piece, which, proximally, may frequently bo seen to be articulated 

 to the subjacent extremity of an interspinous bone or fin-support. 

 A few of these triangular bases of the dorso-caudal fin-rays may be 

 seen both in Figs. 1 and 2, though they are considerably more 

 distinct in specimens Nos. 3 and 5, not figured. 



In specimen No. 1 (Fig. 1), a bone of the shoulder girdle, pro- 

 bably the clavicle of the right side, is seen, but no undoubted trace 

 of either pectoral or ventral fins can be detected in any of the fossils. 



Conclusion. — ^In the Carboniferous specimens before us, we have a 

 fish very closely resembling the Phaneropleuron Andersoni of Huxley, 

 but differing from it in its smaller size, in its somewhat more slender 

 form posteriorly, in the smaller depth of the lower lobe of the caudal 

 fin, and apparently also in the greater extension forwards of the 

 dorsal fin. As it is evidently at least specifically distinct, I propose 

 to bestow on it the title of Plianeropleuron elegans. 



The genus Phaneropleuron is thus ■common to the Upper Devonian 

 and Lower Carboniferous formations. It is one of the most in- 

 teresting of the PalEeozoic Ganoids, as showing the intimate relations 

 subsisting between the ancient Crossopterygians with acutely lobate 

 pectorals and ventrals, and the remarkable recent types, Lepidosiren, 

 Protopterus, and Geratodus. One cannot fail to be struck, as Prof. 

 Huxley has already indicated,^ with the many points of resemblance 

 which this genus bears to Lepidosiren, in the general form of the 

 fish, in its thin circular scales, and in many points in the structure 

 of its internal skeleton. But from the true Dipnoi, with which Dr. 

 Oiinther now unites the Devonian Dipterus, and the Carboniferous 

 Ctenodus,^ it differs, as is well known, materially in its dentition ; 

 and the position of the nasal openings, so peculiar a character in the 

 recent Dipnoi, and in the fossil Dipterus, as Giinther has pointed out, 

 remains yet to be definitely settled. Phaneropleuron must therefore 

 remain, as Prof. Huxley has placed it, the type of a distinct subfamily 

 of Crossopterygidse, viz., Phaneropleurini, and not very far removed 

 from Holopty chilis, and other acutely lobate-membered cycliferous 

 G-anoids of Palaeozoic times. 



My best thanks are due to Mr. Archer, the able and liberal- 

 minded Director of the Edinburgh Museum of Science and Art, for 

 permission to figure and describe the Carboniferous specimens in 

 the Miller Collection ; to my genial friend Mr. Peach, for the loan of 

 the two specimens in his private cabinet, and for having originally 



1 Dec. Geol. Surv. X. p. 26. 



2 proc. Eoyal Soc. March 16, 1871, p. 379. 



