1898-1902. No. 33.] UPPER DEVONIAN FISH REMAINS, 29 



3. There ai'e several small plates or plate fragments which show 

 a more or less mai'ked concentric arrangement oE I he denticles. One of 

 these (S. I. 43.) will be seen in PI. II, fig. S. The denticles are fine, 

 slightly arched, and faintly crenelated. The whole fragment of the plate 

 is slightly arched, but at the same time cannot be characterised as spine 

 shaped. It reminds us of the one described as No. 5 under Ps. ardicus. 

 The inner structure was not investigated. 



Of the fragments here described in greater detail those given in 1 

 in my opinion belong to the large median body plate. Those in 2, I 

 consider to be parts of corniia, whilst the small plates which I ha\e 

 described in 3 may possibly be regarded as plates that were intermediate 

 between the large ones. 



I shall return more closely to this matter in a later section. 

 (Page 37). 



Horizon. All the fragments come from the fish horizon in Skrap 

 Valley. 



Concerning Drepanaspis Gemiindenensis ScHLtJTER. 

 (PL III, figs 5—6, PI. IV, fig. 2). 



As mentioned above, this form plays an important part in the 

 classification of Psammosteus. Before proceding to discuss the syste- 

 matic po.sition of the two new forms of Psammosteus, I will therefore 

 first give an account of one or two new observations regarding this 

 interesting fish, which is described by Traquair^ 



The material at my disposal comes from the classic locality at 

 Gemunden in Himsruck and was acquired through Dr. F. Krantz 

 at Bonn. 



Traquair and .several subsequent investigators, as I have before 

 emphasised, strongly maintained the close relationship of the enigmatic 

 Psammosteus fragments and Drepanaspis, (Page 22). 



In Traquair's opinion it will not be possible to determine how 

 close this relationship is until we have succeeded in studying the 

 microscopic structure of Drepanaspis, and the configuration of the body 

 and the form of the body plates in Psammosteus. 



As regards the microscopic structure, it was found comparatively 

 easy to study it in my specimens. Even the first microscopic sechons 

 that I obtained from one of the large body plates gave a good picture 



1 The Lower Devonian Fishes of Gemunden. (Transactions Roy. Soc. Edinburgh. 

 Vol. XL, 1903, p. 733). 



