190 CLASSIFICATION OP FISHES. 



(B. ornatissimus, fig. 25.), which constitute his order 



Plectognathi : this name, however, we retain, since, by 

 the anatomical investigations of this eminent naturalist, 

 the true nature of the gills were first made known. 

 The most general characters belonging to this group 

 will now be noticed in the order of their prevalence. 

 In the first place, they are universally destitute of 

 true or imbricate scales : the body is soft and naked, 

 as in the Chironectidce, or frog-fish ; or it is hard and 

 coriaceous : in the Balistidce, or file-fish, the skin is 

 hard, and scored * into diamond-shaped patterns (fig. 



26.) : when magnified (a), the 



oq «'ps /*?■* granulations are distinctly seen, 



til' I the interstices being; smooth. In 



^r' f others, the body is either covered 



IIP .\{ ■■'"} |s with spines, Or incased with 



^ % WJk WM ^ bony plates, the sutures of which 



JH ,-y _ fit to each other, and do not, 



as in ordinary fishes, lay in an 



imbricate or tile-like manner upon each other. The 



skeleton is neither strictly osseous, nor cartilaginous, but 



is a mixture of both structures ; presenting a gradation 



from the soft and cartilaginous structure to that which 



is hard and truly osseous : the assertion, therefore, that 



its ec entire general structure is that of ordinary fishes," 



is not borne out by fact ; since M. Cuvier himself 



acknowledges, that, in the majority, the bones are semi- 



* Scored or reticulated : we use this term to denote the peculiar reticu- 

 lated markings on the shagreened skin of certain Balistidce, which give 

 them, at tirst, the appearance of possessing diamond.shaped scales. 



