170 GANOID FISHES OF THE CARBONIFEROUS FORMATION. 



the occiput and extending to the dorsal fin, is a row of large and conspicuous median 

 imbricating scales (fig. 6), each emarginate in front, pointed behind, and becoming 

 more and more acute as the dorsal fin is approached; externally these scales are 

 sculptured with prominent longitudinal ridges. Behind the dorsal fin, acutely pointed 

 scales run along the upper margin of the caudal body-prolongation in the usual manner. 



1 have not seen the pectoral fin, and only in one specimen are some imperfect remains 

 of a ventral discoverable, this being placed slightly in front of the commencement of the 

 dorsal. The dorsal fin commences behind the top of the arch of the back and extends 

 to the commencement of the tail-pedicle; its longest rays have only about half the length 

 of the base of the fin, and as they become very gradually elongated in front, and remain 

 pretty long behind, a peculiarly rounded and proportionally somewhat long-based form 

 of dorsal is here produced, which is very different from the high triangular-acuminate 

 contour which is prevalent in this family. The anal is somewhat similarly shaped, but 

 has a shorter base, for although the termination of its base is opposite that of the dorsal, 

 it commences a little further behind. The caudal fin, arising from the lower margin 

 of a powerful body-prolongation, is not bifurcated, but assumes a somewhat triangular 

 shape, with the posterior margin only gently concave; its anterior rays being com- 

 paratively short, and then gradually diminishing posteriorly. The rays of these fins are 

 nowhere seen to dichotomise, but become simply attenuated distally ; they are divided 

 by transverse articulations, which are distant enough to leave the joints longer than 

 broad; externally they are ganoid and distinctly striated in the direction of their length. 



No fulcral scales are observable on the anterior margin of any of the fins. 



Observations. — In its non-bifurcate caudal and rounded, non-acuminated and 

 proportionally long-based dorsal fin, this remarkable fish, which in 1SS1 I adopted as 

 the type of a new genus, Holurus, contradicts the definition of the Palseoniscidse given 

 by me at the commencement of this monograph; and in the want of dichotomisation 

 of the fin-rays it also differs from hitherto described genera belonging to this family 

 (with the exception of Eanjlepis, Newberry). Nevertheless, the structure of the fish 

 being in other respects so decidedly Palseoniscoid, I feel constrained to retain it in the 

 Palseoniscidse. 



The specific name is after the late Mr. Walter Park of Langholm, to whose zeal as 

 a collector the finding of many interesting specimens of the Eskdale fishes was due. 



Geological Position and Locality. — Near Glencartholm, Eskdale, in the fish-beds of 

 Lower Carboniferous age (Calciferous Sandstone Series). 



