﻿550 ACTINOPTERYGII. 



remote, relatively large, "with closely articulated rays ; median fins 

 large, with distinct fulcra, the rays with distant articulations and 

 ornamented by longitudinal striae. Dorsal and anal fins arising at 

 the dorsal and ventral gibbosities respectively, extending close to 

 the origin of the caudal fin, much elevated in front, the maximum 

 height of the dorsal equalling at least one-third the depth of the 

 trunk at its origin. Scales of flank deep and rhombic, those dor- 

 sally and ventrally and towards the end of the caudal region nearly 

 equilateral ; ornamentation consisting of very fine parallel striae, in 

 the direction of the long axis of the principal flank-scales, but 

 somewhat oblique on those above and below. 



Form, fy Loc. Calciferous Sandstones (Cement-stone Group): 

 Eskdale, Dumfriesshire. 



P. 4060. Imperfect typical specimen, wanting paired fins, in 

 counterpart. Purchased, 1883. 



P. 4061. Small imperfect specimen, with remains of pelvic fins. 



Purchased, 1883. 



The following species have also been determined, but there are 

 no examples in the Collection : — 



Platysomus circularis, Newberry & Worthen, Pal. Illinois, vol. iv. 



(1870), p. 347, pi. iv. fig. 2.— Coal-Measures ; Mazon 



Creek, Illinois. 

 Platysomus orbicularis, Newberry & Worthen, ibid. pi. iii. fig. 1 



(no description). — Coal-Measures ; Illinois. 



The so-called Platysomus fischeri, Arndt (Bull. Soc. Imp. Nat. 

 Moscou, vol. xxiii. 1850, pt. i. p. 88, pi. i.), is founded upon the 

 tail of a bony (probably physoclystous) Tertiary fish, from the 

 neighbourhood of Simferopol. 



Of the remarkable Upper Permian genus Dorypterus (E. F. 

 Germar, in Minister's Beitr. Petrefakt. pt. v. 1842, p. 35) there are 

 no examples in the Collection. This fish still requires satisfactory 

 elucidation, but is evidently related to the Platysomatidae, as indi- 

 cated by the great development of the azygous fin-supports, which 

 are sometimes at least in part mistaken for dermal structures. So 

 far as the absence of flank-scales is concerned, Dorypterus bears the 

 same relation to the typical Platysomatidae as Phanerosieon with 

 respect to the typical Palaeoniscidae. A single species is recognized 

 thus : — 



Dorypterus Iwffmanai, E. F. Germar, in Miinster's Beitr. Petre- 



I 



