1849.] EGERTON ON THE GA.NOIDEI HETEROCERCI. 7 



itself is covered with scales to its extremity. Lord Enniskillen has 

 also a specimen of a young individual of this species seven inches in 

 length. It differs from the mature fish in being less deep in pro- 

 portion to its length. 



Pal^oniscus decorus, Egerton. Pl. II. 



Whether we consider the elegant form and proportions of this fish, 

 or the graceful tracery on the head, or the varied form and arrange- 

 ment of its delicate scales, it must rank as one of the most beautiful 

 species of this beautiful genus. It is rare to find among fossil fishes 

 a highly sculptured character of the cranial bones, without the least 

 trace of ornament on the scales of the nape and those im.mediately in 

 contact with the thoracic girdle. Such however is the case in this 

 species. All the head bones are covered with an elegant tracery of 

 distinct lines running in tortuous courses, sometimes bifurcating, 

 sometimes inosculating and forming intricate patterns of extreme 

 beauty. The scales are thin and perfectly smooth, with entire mar- 

 gins. Those on the back are scallop-shaped, and arranged like the 

 plates of scale-armour. In advance of the dorsal fin are four large 

 saddle-shaped scales decreasing in size from the front. Round the 

 base of the fin the scales are small and of various shapes, arranged 

 in an elegant tessellated pattern. The ventral scales are oblong, and 

 with the exception of the large plate in advance of the anal orifice, 

 considerably smaller than those on the flanks. The latter are oblong 

 on the anterior part of the body, rather higher than wide, but they 

 gradually assume a rhomboidal outline as they approach the central 

 region. The anterior margin of the dorsal fin is ornamented with a 

 delicate fringe of fine scales ; the rays composing it gradually elongate 

 up to the eleventh or twelfth, v/hich is the longest. This character 

 resembles the arrangement of the dorsal fin of Eurynotus. The tail 

 is of very elegant proportions ; the upper lobe attenuates very gradually 

 and is invested with scales to its minutest extremity. This species is 

 from the coal shale of Commenterie inAuvergne. Lord Enniskillen 

 has a specimen of Palceoniscus, stated to have been found near Ilfeld 

 in the Hartz, which has considerable resemblance to this species. 

 Pal.eoniscus arcuatus, Egerton. Pl. I. fig. 1. 



This species has some resemblance to the preceding, but is a 

 shorter and deeper fish. The line of the back from the head to the 

 dorsal fin is gracefully arched, and the dorso-ventral series of scales 

 are more curved both above and below the lateral line in the an- 

 terior part of the body than is usual in this genus. The scales are 

 smaller than those of Palceoniscus decorus and thicker. The fine 

 strise denoting the lines of growth are clearly defined. The bones of 

 the head are covered with flattened plicae. The teeth in the lower 

 jaw are numerous and very regular. The fins resemble those of 

 Palceoniscus decorus, but the dorsal fin is inserted nearer to the head 

 than in that species. The tail is wanting. This species is from the 

 coal shale of Goldlauter. 



