DESCKIPTION OF FKAGMENTARY FOSSILS 407 



scaled ganoids existed side by side in the American Jura as tliey did in 

 the, European. The name Amiopsis, first proposed by Kner for an im- 

 perfect Cretaceous fish resembling Avnia, is used here in lieu of a more 

 definite title, and implying that the remains are supposed to be Amioid, 

 but the genus is indeterminable. The specific title is given in honor 

 of Mr N. H. Darton, who discovered all the remains described in this 

 paper. 



FIN FRAGMENTS 

 Plate 48, figure 3. Genera and species not determined. 



A very interesting fin structure is that shown one-third larger than 

 natural size in figure 3 of plate 48. Nothing is known of the fish it be- 

 longed to, and little can be said of the specimen itself except that it is 

 peculiar in having the anterior margin developed into a strong, spini- 

 form cutwater through coalescence of enlarged fin rays. The latter are 

 not articulated in their proximal portions, and the short, inosculated 

 outer ones apparently not at all. The arrangement of these external rays 

 is curious, and at first sight suggestive of fulcra. They are distinctly fin 

 rays, however, and have nothing to do with the latter structures. The 

 smaller rays adjoining the cutwater are all finely articulated, and are of 

 about uniform size. There can be little question that the appendage 

 here shown is a pectoral fin, with the rays and cutwater preserved in 

 their natural relations. That there has been little or no displacement is 

 shown by the parallelism and proximal origin of all the va,js from the cut- 

 water downward to the posterior margin. A smooth coating of ganoine 

 covers all the rays of the cutwater. 



