74 OLD RED SANDSTONE EISHES. 



which had become current through the writings of such distinguished men as 

 Agassiz and Hugh Miller. They were fiercely combated by Sir Philip Grey- 

 Egerton in the following words : — " Having read both sides of the question with 

 great care, my own impression is that Prof. Eichwald may perhaps have included 

 in his genus Asterolepis some fragments which he subsequently ascertained 

 (through the more perfect Scotch specimens sent to Russia by Dr. Hamel) to 

 belong to the genus Pterichthys of Agassiz, and hence discarding the majority, 

 namely, Asterolepis proper, assigns this name to the minority, to the exclusion of 

 the Agassizian name. In the meantime Prof. Agassiz, then engaged upon his 

 'Poissons fossiles du vieux Gres rouge,' received through Prof. Bronn, from 

 Eichwald himself, specimens of his Asterolepis which had no reference to Pterichthys, 

 but were identical with the genus Chelonichthys established upon specimens 

 brought over from Russia by Sir Roderick Murchison, and of which other 

 specimens were found in the Orkney beds. On making this discovery he at once 

 relinquished his own name Chelonichthys, and adopted Asterolepis of Eichwald. 

 If now it is sought to supersede Pterichthys of Agassiz by Asterolepis of Eichwald, 

 it is surely just that the term Chelonichthys should be retained for Eichwald' s 

 rejectamenta, rather than Homosteus of Asmuss, a name of much later date than 

 that of Agassiz." l 



Most unfortunately, however, for his contention, Sir Philip here overlooked the 

 crucial fact mentioned above, and which was specially insisted on by Pander, namely, 

 that Agassiz himself figured as Asterolepis ornata of Eichwald a head-plate which, 

 far from having (t no reference to Pterichthys," is the median occipital if not of 

 Pterichthys, then of a very closely allied form indeed. So far, therefore, as the 

 " Asterolepis of Stromness " is concerned his argument falls to the ground. 



Had Pander succeeded in establishing the absolute identity of Pterichthys 

 with Asterolepis, the former name would certainly have had to be be cancelled in 

 favour of the latter. But, as we shall see more fully further on, a ground of dis- 

 tinction between the genera was sought to be established by Beyrich, 2 Lahusen, 3 

 and Zittel 4 on the supposed articulation of the arms of Pterichthys to a special 

 pair of plates {thoracic, Egerton ; ceinture thoracique -{-plaques articulaires, Agass.), 

 which plates certainly do not exist in Asterolepis, in which Pander showed that 

 these appendages were directly articulated to the anterior ventro-lateral. But 

 in 1888 5 1 proved the non-existence of these " thoracic " plates in Pterichthys, and 

 showed that its pectoral limbs were articulated precisely as in Asterolepis, while 

 at the same time I drew attention to a character which seems quite sufficient to 



1 ' Quart. Journ. Geol. Soc.,' vol. xvi, 1859, p. 122. 



2 ' Zeitschr. deutsch. geol. Gesellsch.,' 1877, p. 754. 



3 ' Trans. Imp. Min. Soc, St. Petersburg,' vol. xv, 1880, p. 



4 ' Handbuch der Palaeontologie,' vol. iii, pt. i, pp. 153 — 157. 



5 ' Geol. Mag.' (3), vol. v, p. 508. 



