Elasmohranchii. 



83 



The first table-case on the left and the adjoining- wall-case are Wall-case, 

 filled with numei'ous spines and other dermal appendages of ^o* !• 

 cartilaginous fishes, perhaps mostly Elasmobranchs, which 

 cannot yet be precisely determined ; they are conveniently Table-case, 

 grouped together as Jc7ii;/i7/o^(M-?<ZiYes (" fish-spine-stones "). [See 

 Fig. 111.] 



The earliest evidence of the sub-class is placed here, namely, 

 the dorsal fin-spines from the Ludlow Bone-bed (Upper Silurian) 

 and the Old Red Sandstone, bearing the name of Onchus. 

 Gtenacanthics is founded upon dorsal spines from the Carboni- 

 ferous. The huge Oracanfhus pustuloses (PJwderacanthus}, three 

 feet in length, from the Carboniferous Limestone of Bristol, is 

 the largest ichthyodorulite known ; and there are also triangular 

 paired spines of considerable size from the same formation, 



Fig. 111. — Spines of Elasmobranch ami ChimaeroiU Fishes. 

 «, Aeanthias (recent) ; l>, Callorhynelnis (recent) ; c, Macha-racanthus (Devonian) ; 

 d, Hybodus (Jurassic) : e, Asteracanthus (Jurassic) ; /, Squaloraja (Lias) ; 

 (/, Gyracanthus (Carboniferous) ; k, Jidestcx (Cai'boniferous) ; ;, Pleuracanthus 

 (Carboniferous). 



which, are named Oracanthus Milleri, and provisionally associated 

 with several flat dermal plates having a corresponding orna- 

 mentation. Spines of Edestes (Fig. lll/i) occur in the Car- 

 boniferous of N. America, Australia, and Russia, and are 

 remarkable for their curvature and the great size of the posterior 

 denticles ; the latter are in the form of serrated teeth, and led 

 their first discoverer. Prof. Leidy, to conclude that the fossils 

 were fragments of jaws. Gyracanfhus (Fig. lllg) occurs abun- 

 dantly in the British Carboniferous, and is i^epresented both, by 

 the well-known paired spines (with an ornament of angulated 

 ridges, and ordinarily abraded extremity), triangular dei^mal 



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