662 



Fam. 2. Polypterini. 



Polypterus bichir. 

 Fam. 3. Amiidce. 



Amia calva. 



Ordo II. CHONDROSTEI. 



Fam. 1. Acipenserini. 



Acipenser nacarii. 



From these facts it follows that the osseous fishes, notwithstanding 

 their great number, are separated in a very remarkable way into two 

 groups, as shown in the following enumeration : 



Scaphyrhynchus Rafmesquii. 

 Fam. 2. Spatulariee. 

 Spatularia folium. 



Subclassis III. Dipnoi, 



Fam. 1. Sirenoidei. 

 Lepidosiren annectens. 



Fishes with bone- corpuscles. 

 I. All the extensive and higher- 

 organized tribes of Physostomi, 

 J. Mull. ; viz. the 



Siluroidei (except Tricho- 



mycterus). 

 Cyprinoidei. 

 Characini. 

 Mormyri. 

 Salmones. 

 Clupeini. 

 Muraenoidei. 

 Gymnotim. 



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 Pharyngognathi, J. Mull. 



IV. Some smaller and lower-organ- 

 ized tribes of Physostomi, as the 



Cyprinodontes. 

 Esoces. 

 Galaxise. 

 Scopelini. 



Chauliodontida, Bp. 

 Heteropygii. 

 Symbranchii. 



And of the Siluroids, only the genus 

 Trichomycterus. 



V. The PlectognatU. 



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. 



