DORSAL FIN. 115 



and, in a few, it is capable of being raised and 

 depressed as an oflPensive weapon, and inflicts a 

 wound creating great pain. Examples of expanded 

 developement may be seen in the members of the 

 old genus ChcBtodon, among the dories, and in a 

 very beautifully marked tribe, the Acanthuri; in 

 these, the longest rays are often continued for an 

 enormous length in the form of filaments. This 

 will be seen in our representation of 



