﻿3 I 



GANOID FISHES OF THE CARBONIFEROUS FORMATION. 



II.— THE SYSTEMATIC POSITION OF THE PAL^ONISCID^. 



The order of Ganoid Fishes instituted by Agassiz included, in his system of classifi- 

 cation, the following families : — 1. Lepidoides ; 2. Sauro'ides ; 3. Celacanthes ; 4. Pycno- 

 dontes ; 5. Dipteriens ; 6. Acanthodiens ; 7. Cephalaspides ; 8. Acipenserides ; 9. 

 Sclerodermes ; 10. Gymnodontes ; 11. Lopliobr ancles ; 12. Siluro'ides. We have already 

 seen that the genera of Palaoniscidce known to him were distributed in three of these 

 families, viz. the Lepidoides, Sauro'ides, and Acanthodiens, on account of characters 

 which subsequent researches have shown to be either superficial or, in other cases, 

 untenable. 



The anatomical researches of Johannes Miiller 1 into the structure of the recent Ganoids 

 resulted in his detaching from them the Scleroderms, Gymnodonts, Lophobranchs, and 

 Siluroids, the rest being divided into two great groups or sub-orders, as below. 



I. Holostei. — Vertebral column osseous. 



Family 1. Lepidosteini. 

 2. Polypterini. 



II. Chondrostei. — Skeleton partially cartilaginous ; the vertebral column consisting 



of a soft chorda instead of vertebral bodies. 

 Family 3. Acipenserini. 

 4. Spatularise. 



Of the fossil Ganoids Midler stated that they have in their squamation more resem- 

 blance to the living Holostei than to the Sturgeons, and that he considered the separation 

 of the families of Lepidoids and Sauroids as artificial. He did not, however, attempt 

 definitely to remodel the classification of the fossil Ganoids, though he stated his opinion 

 that characters of prime importance were to be found in the condition of ossification of 

 the vertebral column, the presence or absence of fulcra on the fin-margins, and whether 

 these fulcra, when present, were in single or double series. 



Almost immediately after, in fact during, the publication of Midler's researches, the 

 recent Amia was shown by Carl Vogt also to possess anatomical characters which 

 demanded for it a position among the Ganoids. 2 The place of the Amiadce in Miiller's 

 classification would, of course, be with the Holostei. 



In the classification of fossil fishes proposed by Giebel in 1848, 3 Miiller's great divi- 



1 ' Ueber den Baa und die Grenzen der Ganoiden, und iiber das natiirlicbe System der Eische,' 

 Berlin, 1846 (read before the Berlin Academy of Sciences in December, 1844). 



2 " Quelques Observations sur les caracteres qui servent a la classification des Ganoides," ' Annales 

 des Sciences Naturelles,' 3 ser., t. iv, 1845, pp. 53 — 68. 



3 'Fauna der Vorwelt,' vol. i, pt. 3, Leipzig, 1848. 



