48 



OLD RED SANDSTONE FISHES. 



proportion, and are more incurved than in Eu.. LyeUii or Eu. Agassizii. There appear to 

 be about thii'ty prjedorsal scales in each series instead of twenty-five, and the scales are 



Fig. 19. 



Diagram outline of the head-sliield of Eucephalaspis Powriei. 



narrower in proportion to their length and of less thickness apparently than in Eu. Lyellii. 

 The head measures If inch, the whole 5^ inches in length, giving a ratio of 1 to 

 3'14, instead of 1 to 2'6. The ornament in this species is very finely tubercular. 

 In Mr. Powrie's magnificent specimen, figured in PI. XI, the ornament can be seen in 

 parts with a lens, and may also be traced on many of the scales. 



General Remarks. — The grand specimen of fig. 1, PI. XI, was obtained by Mr. 

 Powrie at Ley's Mill, near Arbroath. It has been most carefully developed, and shows the 

 concave side of the head-shield, and the body twisted so as to bring the dorsal surface to 

 the left side, as one looks at the specimen. Other head-shields, detached from the body, 

 have come to hand, and one, belonging to Mr. Powrie, is figured in PI. X, fig. 5. 

 A similar specimen is in the collection of the Rev. Hugh Mitchell, of Craig, near 

 Montrose. The specimen figured in pi. 1, fig. 1, of the ' Poissons fossiles,' and now 

 in Sir Philip Egerton's collection, appears to belong to this species. It is most erroneously 

 drawn in the figure referred to. The concave surface of half a head is presented with the 

 half of the attached body, showing the position of the dorsal and caudal fins ; but the 

 dorsal series of scales is not preserved as drawn by Mr. Diiikel, the two sets of opposite 

 sides being confused in a mass. The lateral series present the same appearance as those 

 of ]\Ir. Powrie's specimen ; but I could not count as many as thirty praedorsal. The 

 structure of the dorsal and caudal fins is not shown. 



