XXIII 



ACANTHOPTERYGII 



715 



Fam. 1. Trachypteridae. Mouth very protractile; ventral 

 fins more or less developed, with 6 to 9 rays, or reduced to a 

 single long ray ; no anal fin ; vent about the middle of the body ; 

 caudal rays, if present, divided into two fascicles, the upper some- 

 times much prolonged and directed upwards. 



FIG. 432. Trachypterus iris. x 1. (After Cuvier and Valenciennes.) 



Two genera. The most generalised is Tracliypterus, of which 

 probably only 10 forms are entitled to specific distinction. The 

 best known species is T. arcticus, the Deal-Fish or Northern 

 Ribbon-Fish, which reaches a length of 8 feet or more, and of 

 which a few specimens have been stranded on the coasts of 

 Scotland. Nilsson, who has observed these fishes alive on the 

 Scandinavian coast, says they approach the shore at flood-tide on 

 sandy shelving bottoms, and are often left by the retreating 

 waves ; that they move with one side turned obliquely upward, 

 and that they lie on the side like Fiat-Fishes on the bottom in 

 2 or 3 fathoms of water. Eegalecus differs in the presence of a 

 single ray to the ventral and the absence of the caudal fin. 

 Some 5 or 6 species may be distinguished. E. glesne, the Oar- 

 fish, or " King of the Herrings," is the best known and the 

 largest species, reaching a length of over 20 feet. About 25 



