548 EA1ISAY H. TEAQTJAIE ON AMBLYPTEKTJS, 



30. On the Agassizian Genera Amblypteetjs, Pal^oniscus, 

 Gyeolepis, and Ptgopteeus. By Ramsay H. Teaquaie, 

 M.D., F.R.S.E., E.G.S., Keeper of the Natural-History 

 Collection in the Edinburgh Museum of Science and Art. 

 (Read May 9, 1877.) 



What is an Amhlypterus ? What is a Palceoniscus ? How do 

 we distinguish them ? What special reasons have we for 

 referring any of our smaller Carboniferous fishes to the one or the 

 other genus ? These are questions to which, I fear, few collectors 

 of Carboniferous fossils could offer very definite answers, and for the 

 very good reason that the definitions of these two genera, which 

 are found in the works usually consulted by palaeontologists, are, it 

 must be owned, of a somewhat unsatisfactory nature. 



Gyrolepis and Pyr/opterus also are terms frequently met 

 with in lists of fossils from British Carboniferous localities. But 

 by what characters do we distinguish Gyrolepis as a genus ? Or 

 what are the special marks which justify us in assuming any of our 

 larger Carboniferous Paloeoniscidce to be generically identical with the 

 Pygopteri of the Magnesian Limestone and Kupferschiefer ? Here, 

 again, we shall find our subject enveloped in an obscurity which can 

 only be dispelled by fresh and careful original observation in a 

 field which, since the days of the illustrious Agassiz, has been com- 

 paratively little trodden. 



The present communication embodies the results of my own 

 recent investigations into these subjects, though there is room and 

 need for much additional inquiry, as is self-evident from the nature 

 of the remains with which we have to deal. 



Amblypteetjs and Palceoniscus. 



The definition of Amhlypterus given by Agassiz in his " Tableau 

 synoptique " is as follows : — 



" Toutes les nageoires trcs-larges et composees de nombreux 

 rayons, P. tres-grandes ; A. large ; D. opposee a l'intervalle entre 

 les V. et l'A. ; point de petits rayons sur le bord des nageoires, 

 excepte au lobe superieur de la queue. Ecailles mediocres " *. 



Of Pala?oniscus, on the other hand : — 



" Toutes les nageoires mediocres, de petits rayons sur leurs bords ; 

 D. opposee a l'espace entre les V. et l'A. Ecailles mediocres ; 

 quelques especes en ont d'assez grandes, et le corps plus large et 

 plus court que les autres. II y a toujours de grosses ecailles impaires 

 en avant de la D. et de l'A " f . 



Both genera are elsewhere stated to have the teeth " en brosse 

 extremement fine " or " en brosse " J. The statement as to the 



* Poissons Fossiles, vol. ii pt. 1, p. 3. t Ibid. p. 4. 



J Ibid. p. 30, p. 42 &c. 



