DETAILS OF FIGURED SPECIMENS 405 



the specific identity. Total length, 16 centimeters ; length of head, 4 

 centimeters. 



One of the halves of a small specimen preserved in counterpart is shown 

 in plate 47, figure 2j some of the details being added from the opposite 

 slab. The view here presented is part ventral and part lateral, the pos- 

 terior part of the body lying on its right side. As the total length is only 

 about 12 centimeters, the pectoral fins and mandibles are seen to be 

 relatively larger than in preceding examples, and the scales at the base 

 of the caudal fin are enormously enlarged. No basal supports for any 

 of the fins are preserved ; there is likewise no trace of a gular plate nor 

 of verebral rings. A complete series of laminar branchiostegals is ex- 

 hibited, in front of which lies a small dentigerous plate supposed to be 

 the fused premaxillse. 



The remaining figures of plate 47 are of small forms preserved in 

 counterpart. Figures 4 and 5 show the right and left halves of the same 

 specimen, and are reproduced from negatives without retouching. They 

 show the lateral line very conspicuousl}'- ; also the finely branched caudal 

 fin rays and delicate squamation. The fish is probably an immature 

 example of the same species as the foregoing, and is about half the size 

 of the type specimen. Figure 3 of plate 47 is likewise of a small form 

 with delicate squamation. It has a strong, well ossified maxilla and 

 convex opercular plates. The number of transverse and longitudinal 

 scale-series cannot be counted accurately, but appears to be greater than 

 in other examples. It is probable, therefore, that another species is in- 

 dicated, at present indefinable. None of the specimens exhibit any trace 

 of vertebral centra, ribs, or fin supports. 



Relations to other Species 



More than 40 species of PhoUdophorus have been described from all 

 parts of the world, many of which, however, are founded on imperfectly 

 determinable material. They range from the Upper Trias to the Upper 

 Jura, and with the exception that later forms are often more highly or- 

 namented than the earlier, exhibit remarkably constant characters. On 

 the basis of scale ornamentation two series are recognizable, one having 

 and the other being without serrated scales. The present species finds 

 its place among the smooth-scaled forms, and is not far removed from 

 the type species, P. bechei Agassiz, from the Lower Lias. The Eugnathidse 

 have precisely the same range as Pholidophoridse, and any inferences as 

 to stratigraphic correlation derived from the one are equally applicable 



LVIII— BuLi,. Geol. Soc. Am., Vol. 10, 1898 



