72 



Royal Society .- 



Fishes with bone-corpuscles. 



I. All the extensive and higher- 

 organized tribes of Physostomi, 

 J. Mull. ; viz. the 



Siluroirlei (except Tricho- 

 mycterus). 



Cyprinoidei. 



Charaeini. 



Mormyri. 



Salmones. 



Clupeini. 



Muricnoidei. 



Gymnotini. 



II. All the Ganoidei. 



III. The Sirenoidei. 



IV. Of the Acanthopteri, only the 

 genus Thynnus, Cuv. 



Fishes without bone-corpuscles. 



I. All the numerous tribes of the 

 Acanthopteri, with the excep- 

 tion of the genus Thynnus. 



II. All the Anacanthini, J. Mull. 



III. The Pharynyoynathi, J. Mull. 



IV. Some smaller and lower-organ- 

 ized tribes of Physostomi, as the 



Cyprinodontes. 

 Esoces. 

 Galaxiac. 

 Scopelini. 



Chauliodontida, Bp. 

 Ileteropygii. 

 Symbranchii. 

 And of the Siluroids, only the genus 

 Trichomycterus. 



V. The Plectoynathi. 



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 meantime, 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 are 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 Quekett first showed in the genera 

 Orthagoriscus and Lop/iius, 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 



