The Squamipinnes 409 



yellow, is common in Polynesia; Zebrasoma veliferum, cross- 

 barred with black, is also common. 



Ctenochcztus (strigosus), unlike the others, is herbivorous and 

 has its teeth loosely implanted in the gums. This species, black 

 with dull orange streaks, was once tabu to the king of Hawaii, 

 who ate it raw, and common people who appropriated it were 

 put to death. 



In Xesurus the caudal lancelet is replaced by three or four 

 bony tubercles which have no sharp edge. Xesurus scalprum 

 is common in Japan, and there are three species or more on 

 the west coast of Mexico, Xesurus punctatus and Xesurus 

 laticlavius being most abundant. 



In Prionurus (microlepidotus] of the tropical Pacific the 

 armature is still more degraded, about six small plates being 

 developed. 



In Acanthurus (Monoceros, naseus), the unicorn-fish and its 

 relatives, the ventral fins are reduced, having but three soft rays, 

 the caudal spines are very large, blunt, immovable, one placed 

 in front of the other. In most of the species of Acanthurus 

 a long, bony horn grows forward from the cranium above the 

 eye. This is wanting in the young and has various degrees of 

 development in the different species, in some of which it is 

 wholly wanting. The species of Acanthurus reach a large size, 

 and in some the caudal spines are bright scarlet, in others blue. 

 Acanthurus unicornis, the unicorn-fish, is the commonest species 

 and the one with the longest horn. It is abundant in Japan, 

 in Hawaii, and in the East Indies. 



Axinurus thynnoides of the East Indies has a long, slim body, 

 with slender tail like a mackerel. 



Suborder Amphacanthi, the Siganidae. The Amphacanthi 

 (a/u<j>i, everywhere ; at<av6a, spine) are spiny-rayed fishes cer- 

 tainly related to the Teuthidida, but differing from all other 

 fishes in having the last ray of the ventrals spinous as well as 

 the first, the formula being I, 4, I. The anal fin has also six 

 or seven spines; and the maxillary is soldered to the premax- 

 illary The skeleton is essentially like that of the Acanthu- 

 rida. 



The single family, Siganida, contains fishes of moderate 

 size, valued as food, and abounding about rocks in shallow 



