INTRODUCTION. XV 



miliar type is the murana, or eel, or of fishes 

 which have an elongated form, a thick and soft 

 skin, which scarcely suffers their scales to appear, 

 but few crests and caeca. Almost all have nata- 

 tory bladders, which frequently exhibit singular 

 forms. 



V. Lophobranchii. That singular figure which we meet 



with, called the hippocampus, or sea-horse, is a 

 prominent instance of this confined order; the 

 distinctive characters of which are drawn from 

 peculiarities in the gills, which, " instead of be- 

 ing, as usual, pectiniform, are divided into little 

 round tufts, singularly disposed in pairs along 

 the branchial arch.' 7 The lophobranchii are also 

 cuirassed from one extremity of the body to 

 the other; this renders them mostly angular in 

 figure. 



VI. Plectognathi. This order offers forms of the most 



grotesque figures, as seen in the inflated bodies of 

 the balloon and globe fishes, and in that of the 

 moon-fish. The plectognathi are either very pug- 

 nacious in their own disposition, or otherwise 

 very liable to the attack of others, as their ample 

 means of offence and defence testify : some are 

 surrounded with prickles, or are armed with 

 spear-like excrescences, or formidable teeth. Other 

 distinctive characters of this orde are derived 

 from peculiarities in the bones of the head. The 

 balistes, which is a member of this order, is so 

 named from its fancied resemblance to the ancient 

 warlike engine called balistes, which projected 

 darts to a great distance. The marine balistes 

 have a long spine inclined on the back, which 



