2722 



THE BONY FISHES AND GANOIDS 



and extinct genera, are all marine fishes, with a practically cosmopolitan distribu- 

 tion; many of them living at great depths, and coming under the denomination of 

 deep-sea fishes. They are also a geologically ancient group, represented by a large 

 number of generic types, both existing and extinct in the Chalk and other Creta- 

 ceous deposits. The only existing forms that frequent the higher strata of the ocean 

 belong to the genera Holocentrum and Myripristis; but even some species of the lat- 

 ter may descend as deep as one hundred and fifty fathoms. The typical genus Beryx 

 has been taken from between three and four hundred fathoms; and from the small 

 size of the eye the forms known as Melamphcees must, in Dr. Giinther's opinion, in- 



GROUP OF SPINE-FINNED FISHES. 



Teuthis (upper figure); Pempheris (on the right); and Polynemus (on the left). 

 (One-fifth natural size.) 



habit still lower levels. Another sign of their deep-water habits is afforded by the 

 high development of the slime-secreting apparatus of these fishes. 



. Of the genera that space permits of our noticing, the most peculiar is Monocen- 

 tris, represented by a single small and rare species from the seas of Japan and 

 Mauritius, and distinguished by the absence of armatures on the gill cover, the 

 large size of the scales, which are articulated so as to form a solid armor, and 

 the reduction of the ventral fins to a single long spine and a few rudimental 

 rays. The fish figured in our illustration ( Trachichthys trailli} represents a genus, 

 with a few species from New Zealand and Madeira, characterized by the short and 



