6 



BEITISH FOSSILS. 



11. — Illustrations of the Structure of the Ccela- 



canthini. 



1. The genera CoEL ACANTHUS and Undina. 



In the " Preliminary Essay upon the Systematic Arrangement 

 of the Fishes of the Devonian Epoch/' prefixed to the tenth decade 

 of the Figures and Descriptions illustrating British Organic 

 Eemains" (1861), I have endeavoured to prove that the genera 

 Ccelacanthus, Undina, and Macropoma constitute a very distinct 

 family of the Crossopterygian Ganoids, to which the term Coela- 

 canthini ought to be restricted. 



At the time of the publication of this essay I was unaware that, 

 in 1858, the late eminent paleontologist, M. ThioUiere, had 

 enunciated the same conclusion in the following terms : — 



La famille des Celacanthes comprendrait a la fois, suivant son 

 auteur, les Sudis de la faune actuelle, le Glyptolepis leptopterus 

 du vieux gres rouge, et le Coelacanfhus granulosus du terrain 

 permien. Ce sont pourtant la trois types ichthyologiques beaucoup 

 trop differents pour etre ainsi reunis. Mais, si I'on exclut les 

 deux premiers et qu'on associe au genre Codacantlius lui-meme 

 les Macropoma de la craie et les Undina du Jura, on obtiendra 

 le noyau d'une famille reellement naturelle, et que, pour eviter 

 la confusion, M. Thiolliere designera par le nom ^ Ortlio-cela- 

 canthes." * 



It is to be regretted that only the abstract of this paper has 

 been published, as it would have been very interesting to learn 

 the grounds upon which M. Thiolllere's conclusion is based, and 

 which are not stated in the Note " whence the foregoing passage 

 is extracted. 



My own view of the common characters of these genera is 

 given in the following definition of the suborder Crossopterygid(B 

 and family Coelacanthini ("Preliminary Essay," p. 26). 



Suborder CROSSOPTEEYGID^. 



Dorsal fins two, or if single multifid or very long ; the pectoral 

 and, usually, the ventral fins lobate ; no branchiostegal rays, but 

 two principal, with sometimes lateral and median, jugular plates 

 situated between the rami of the mandible ; caudal fin diphycercal 

 or heterocercal ; scales cycloid or rhomboid, smooth or sculp- 

 tured. 



Fam. Coelacanthini. 



Dorsal fins two, each supported by a single interspinous bone ; 

 paired fins obtusely lobate; air-bladder ossified. 



Since 1861 I have studied a considerable number of specimens 



* Note sur les poissons fossiles du Bugey, etsur V application de la Methods de Cuvier 

 a leur classement; par M. Thiolliere. Printed in abstract in the "Bulletin de la 

 Societe Geologique de France/' Sc. 2, I. xv., pp. 782-793, 1858. 



