206 



LOWER VERTEBRATES. 



subdivision. All of them are elongated and very much compressed, resembling, as 

 the name tanioid indicates, a band or ribbon ; the lower jaw is more or Jess joromi- 

 nent; large barbed teeth arm the jaws; the dorsal fin is very long, and generally the 

 spinous portion merges into the soft without any break ; the anal fin proper is short, 

 but preceded by numerous rudimentary spines intervening between its commencement 

 and the anus, and the ventrals are represented by scale-like spines or entirely wanting. 



The scabbard-fishes, Lepidopidid^, are those foi-ms which have a distinct and 

 tolerably developed, though small, caudal fin, and whose pectoral fins are modified in 

 a curious way, appearing to be inserted wrong side upwards, for the lower rays are 

 longer than the upper, and diminish upwards. There are at least four genera of this 

 type known. The species are inhabitants of tolerably deep waters. 



The true scabbard-fish, Zepidopus argenteus, has a pointed head, and is of a beauti- 

 ful silvery color. The species is interesting on account of its distribution. It is found 



Fig. 118. — Trichiwrus iepiuruSi thread-fish, cutlass-tish. 



in deep water in the Mediterranean and along the coast of Europe, but more sparingly 

 northward. By the English fishermen it is called the scabbard-fish ; it is, however, 

 quite rare, and not a regular food-fish of the English. In the southern hemisphere it 

 reappears, and after heavy storms is cast ashore on New Zealand about the season when 

 the frost commences, and for this reason is called the frost-fish. It is regarded in New 

 Zealand as being at least one of the best food fishes of the colony ; in the words of Dr. 

 Hector, even " the most delicious fish in New Zealand." 



The hair-tails or cutlass-fishes constitute the family Trichiueid^, and, as the name 

 indicates, have the posterior part of the body elongated and almost hair- or thread- 

 like, and, of course, it is destitute of a caudal fin ; the pectoral fins are of the normal 

 type of structure, and present no distinctive characteristics. , 



The common thread-fish, perhaps better known as the cutlass-fish or sabre-fish, 

 Trichiurus lepturus, is quite widely diffused in the tropical and temperate Atlantic 



