THORNBACKS. 



4i7 



sea fishes is, as Dr. Giinther remarks, perfectly evident from their filamentous fins, 

 which would be irretrievably damaged if their owners did not live at depths 

 where the water is perfectly undisturbed. From the expansion of the extremities 

 of the pelvic fins, Banks's ribbon-fish has been named the oar-fish ; while from a 

 supposed idea that it accompanied the shoals of those fish, it has likewise been 

 designated the king of the herrings. It has been suggested that large ribbon-fish 

 floating on the surface have given rise to many of the reports regarding the sea- 

 serpent ; but, as Dr. Giinther pertinently points out, such dead or dying creatures 

 do not by any means accord with the active movements generally attributed to 

 that mythical monster. Still, however, we believe that a stranded ribbon-fish has 

 been mistaken for a dead sea-serpent. 



The Thornbacks,— Family Notacanthidjs. 



The last family of the great division of spiny-finned fishes we have been 

 considering in the foregoing paragraphs includes only the deep-sea fishes 



risso's thornback (^ uat. size). 



known as thornbacks, all of which are referred to the single genus Notacanth us. 

 These fishes are very abnormal forms, agreeing only with the more typical 

 members of the suborder to which they are referred in the presence of spines in 

 the median fins. Possessing an elongate and somewhat compressed bod} r , covered 

 with minute scales, they are specially characterised by having the dorsal fin 

 composed of a series of low isolated spines, without any soft portion ; while the 

 anal is elongated, with a great number of spines; the pelvic fins being abdominal 

 in position, and comprising more than five soft rays, in addition to several un- 

 articulated ones. In the head the muzzle is prolonged in advance of the mouth ; 

 the moderate-sized eyes are lateral in position ; and the teeth are small and weak. 

 The six known species range from the Arctic Ocean to the Mediterranean, Atlantic, 

 and South Pacific. All are deep-sea fishes, probably dwelling at depths of from 

 a hundred to five hundred fathoms ; although one specimen taken to the south of 

 Yokohama during the voyage of the Challenger is stated to have come from a 

 depth of nearly nineteen hundred fathoms. 

 vol. v. — 27 



