73 



Royal Society : — ' 



Fishes with hone-corpuscles, 



I. All the extensive and hii^licr- 

 orp:anized tribes of Physostomi, 

 J. Miill. ; viz. the 



Siluroidei (except Tricho- 

 mycterus). 



Cyprinoidei. 



Characini. 



Mormyri. 



Salmones. 



Clupeini. 



Mursenoidei. 



Gymnotini. 



II. All the Ganoidei. 



III. The Sirenoidei. 



IV. Of the Acanthopteri, only the 

 genus Thynnus, Ciiv. 



Fishes without hone-corpuscles. 



I. All the numerous tribes of the 

 Acanthopteri, with the excep- 

 tion of the genus Thynnus. 



II. All the Anacanthini, J. Miill. 



III. The Pharyngognathi, J. Miill. 



IV. Some smaller and lower-organ- 

 ized tribes of Physostomi, as the 



Cyprinodontes. 

 * Esoces. 

 Galaxiae. 

 Scopehni. 



Chauliodontida, Bp. 

 Heteropygii. 

 Symbranchii. 

 And of the Siluroids, only the genus 

 Trichomycterus. 



V. The Plectognathi. 



VI. The Lophobranchii. 



As there can be no doubt that most of the higher-organized fishes 

 are amongst those with bone-corpuscles, and as we know that amongst 

 the higher vertebrata, even the lowest, viz. the Perennibranchiata, 

 possess real osseous tissue, it seems to follow that the peculiar dis- 

 tribution of real osseous tissue and of the ''osteoid" structure, as 

 the osseous tissue without corpuscles may be called, has a deeper 

 signification. This will be found by studying the development of 

 the bones in both groups ; and I hope to be able, before long, to pre- 

 sent to the Royal Society some new facts with regard to this matter 

 also ; but in the mean time, until my observations are more complete, 

 I must abstain from further explanation. 



The facts exposed hitherto have had reference only to a great 

 and fundamental structural difference between two extensive groups 

 of osseous fishes. I may now add, that there exist also greater or 

 lesser structural discrepancies amongst the different tribes of each 

 group. But as this is not a suitable occasion for an exposition of 

 the details of this question, I will only say this much : — In the higher 

 fishes, those with real osseous tissue, there exist differences, especially 

 with regard to the form and size of the bone-corpuscles ; and I hope 

 to be able to show that there are peculiar and tolerably well cha- 

 racterized types of them amongst the Ganoids, Siluroids, Salmonidce, 

 Cyprinoids, Clupeini, &c. In the second group there arc more 

 varieties. In some tribes the bones are quite structureless homo- 

 geneous masses, as in the LeptocephalidcE ; in others they have a 

 peculiar fibrous appearance, and consist of a singular mixture of 

 cartilage and osteoid structures, as Quckett first showed in the genera 

 Oi'thagoriscus and Lophius, to which I may add some Balistini ; but 

 in the great majority of the tribes of this group, the bones contain 

 peculiar tubes more or less similar to those of dentine. If these 



