FAINE DU CALCAIRE CARBONIFÈRE DE LA BELGIQUE. 
23 
of the upper lobe of lhe tail. About 50 rays may be countcd in it, rapidlv increasing in length to 
the 10"’, wbich is the longest. The length of lhe base of the dorsal fin is 2 inches; of its longest 
rays 1 The anal fin commences at a distance of 6 % inches behind the tip of the snout; in 
form it also ressemble the anal of Eurynotus, being triangular and acuminate, with short base of 
origin. The length of its base is d Q, inch, which is the same as that of its longest rays ; 
the numher of rays unfortnnately cannot he counted, The caudal is powerfully heterocercal and 
apparently deeply cleft, though it is not in very good préservation, the rays of the upper lobe being 
almost entirely gone, and those of the lower not preserved up to their extremities. The rays of those 
médian fins are tolerably coarse, and divided hy transverse articulations, which are distant enough 
to make the joints appear about twice as long as hroad; conspicuous fulcra are seen on the anterior 
margins of at least the dorsal, and lower lobe of the caudal. 
Remarks. — The form ofthe dorsal fin, and more especially the structure of the head render it 
évident that the ahove descrihed fish, to which I hâve given the generic narne Bencdenius in 
honour of its first descriher, lhe distinguished Professor of zoologie in Louvain, cannot he incîuded 
in the family Palæoniscidæ, but that, on the other hand, it must take its place with those Hetero¬ 
cercal Ganoids whose affinities point more or less in the direction of Platysomus. And among these 
forais, which may be appropriately classed together as Platysomidæ, there seems to me to he 
little doubt that Eurynotus is the one to which the subject of the présent description is most closelv 
allied. it is true that, most unfortunately, the dentition of the two généra cannot be compared. But 
in the general shape of the body and head, in the form of lhe dorsal and anal fins, and of the 
powerfully heterocercal tail, the resemblances of Bencdenius to Eurynotus are ohvious. Equally 
obvions are also the distinctions between them, as seen in the smaller size and shorter base ofthe 
dorsal fin, and ils much more posterior commencement; the delicacy of the pectoral fins, which in 
Eurynotus are very large and powerful and the scutes or large scales of lhe dorsal and ventral 
margins of the body, which form indeed a mos! peculiar feature of the genus. 
Geological Position and Localily. — Discovered hy AI. de Montpellier d’Annevoie in the carbo- 
niferous limestone of Dcnée in Belgium and presented hy him to the Muséum at Louvain. 
Ramsay H. Traquair. M. D. 
Keeper of lhe naturel history collections in the Museumof Science anc! Art at Edinburgh. 
