INTRODUCTfON. XI 



Hence the Ciivieran appellation of this family, " Les Squammipennos.'''' 

 In many of these fishes, even in certain species of the genus Chatodon 

 itself, the lateral line, as in Glyphisodon and Heliastes, cannot be traced 

 beyond the termination of the dorsal fin. 



Examples : — No English species. " Castanheta baia," and " C. ferreira" 

 of Madeira, placed by Cuvier and Valenciennes at the end of Scifenidce. 



Passing over the nearly allied exotic family of Osphromenida,'^ we arrive 

 at a group rivalling, if not exceeding in extent, that even of the Perches : viz. 



Scombrid/s : — The Mackerel tribe. 



A well-known, and, within its proper limits, well-marked group, al- 

 though not easily defined, because dependent upon a combination of cha- 

 racters in various proportions ; not one of which, perhaps, but is occa- 

 sionally liable to aberration. The principal of these, however, are the 

 following. One of the most striking to the eye, and tolerably general, is a 

 peculiar smoothness or apparent nakedness of body, owing to the small ness 

 of the scales. The form is more or less elongated ; the caudal fin is gene- 

 rally furnished with a keel or cuirassed ridge on each side of its base ; it is 

 strong and well forked, ensuring vigour or rapidity of movement ; to which 

 the absence of all protuberances, spines, or teeth about the head and edges 

 of the opercles, joined with a peculiar compactness, simplicity, and closeness 

 of packing observable about the latter, much contributes. The second dorsal 

 fin is almost always elongated, generally high in front, and often separated 

 into detached portions (called spurious fins or finlets) behind. The first 

 dorsal fin is either short, or merely represented by a few short isolated 

 spines without connecting web ; sometimes it is entirely wanting. The 

 anal fin corresponds with the second dorsal, and, like it, either has two or 

 three detached free spines in front, or is separated into finlets behind. 



The prevailing colour of these fishes is silvery-blue or steely, varied 

 with different iridescent tints. Their flesh is much employed for food, but 

 is generally somewhat dry and fibrous. Many of the species are gregarious ; 

 and almost all are endowed with great locomotive energies. 



Examples : — Mackerel, Tunny, Sword-fish, Scabbard-fish, Pilot-fish, 

 Scad or Horse-mackerel, &c. of England ; Cavalla, Atum, Agulha, Espada, 

 Tronbeta, Anchova, Chicharro, &c. of Madeira. 



From these, the genus Zeus (John Dory) may be separated ; typifying 

 a family, Zenida, of which one striking character is a tendency to the 

 developement of dermal bony plates, analogously to the mailed Silurida, 



* The celebrated Goramy tribe (" Pharyngiens Labyrinthiformes," Cuv.) ; in form and outward 

 characters closely resembling the ChcBtodonlida, but differing in a curious internal apparatus con- 

 nected with the gills ; which is supposed, by fulfilling the office of a reservoir to these organs, to 

 account for some remarkable peculiarities of habit in certain of these fishes ; enabling them to leave 

 the water, and to stray so far sometimes from its vicinity, that in India, as Cuvier relates, they are 

 imagined to have fallen from the sky. 



B 4 



