630 FISHES. 



ingly fine and deciduous scales, which are scarcely imbricate, 

 lying in subhexagonal impressions ; vent situated at no great 

 distance from the caudal fin. Head compressed, with the snout 

 very short, and with the cleft of the mouth very wide. Teeth 

 pointed, unequal in size, those of the intermaxillaries and of the 

 mandible being the longest ; maxillary finely denticulated ; 

 vomer with a pair of fangs ; palatine bones and tongue with 

 smaller pointed teeth. Eye of modei'ate size. Opercular portion 

 of the head narrow. A fleshy barbel in the centre of the hyoid 

 region. Dorsal opposite the anal, close to the caudal ; pectoral 

 and ventral fins feeble, the latter inserted behind the middle of 

 the length of the body. Series of phosphorescent dots run along 

 the lower side of the head, body, and tail. Gill-opening very 

 wide. Pyloric appendages none. 



Three species are known ; beside specimens which were 

 found floating on the surface, others have been dredged from 

 depths varying between 450 and 1800 fathoms. 



Fifteenth Family — Salmonid^e. 



Body generally covered with sccdcs ; head naked; harhels 

 none. Margin of the v/pixr jaio formed hy the intermaxillaries 

 mesially, and hy the maxillaries laterally. Belly rounded. A 

 small adipose fin behind the dorsal. Pyloric appendages gener- 

 cdly numerous, rarely ahsent. Air-bladder large, simple ; 

 pseuddbranchicc present. The ova fall into the cavity of the 

 abdomen before exclusion. 



Inhabitants of the sea and freshwater ; the majority of 

 the marine genera are deep-sea forms. The freshwater forms 

 are peculiar to the temperate and arctic zones of the Northern 

 Hemisphere, one occurring in New Zealand ; many fresh- 

 water species periodically or occasionally descending to the 

 sea. One of the most valuable families of the class of 

 fishes. No fossils of the freshwater forms are known ; but of 

 the marine genera, Osmerus occurs in the greensand of Ibben- 

 busen, and in the schists of Glaris and Licata ; a species of 



