86 NORTHERN ZOOLOGY. 



biting the Mediterranean, and another the sea of Japan. Lophotes contains only 

 a single species, which inhabits the Mediterranean, but is very rarely caught. It 

 has the top of the head elevated by a high bony crest, to which there is articulated 

 a long and strong spine, having a membranous border ; the dorsal, continued from 

 this spine to the point of the tail, has short, simple rays, and there is a very small, 

 distinct caudal : the ventrals are scarcely perceptible. The teeth are pointed and 

 widely set. 



SIGANOIDE.E.— LES THEUTYES. 



This family, which is peculiar to the warmer districts of the ocean, is as closely 

 allied to the Scomberoideee as the preceding one ; but by other characters, such as 

 the lateral armature of the tail in some genera, or the spine imbedded before the 

 dorsal, in others. In all, the body is compressed, oblong, and surmounted by a 

 single dorsal ; the mouth is but slightly, or not at all, protractile ; each jaw is 

 armed with a single row of cutting teeth ; the palate and tongue are toothless ; and 

 the gill-rays are four or five in number. The Siganoidese live on fuci and other 

 sea-weeds, and their intestines are capacious, in conformity with their herbivorous 

 habits. The genera are few in number. The first, Siganus, is distinguished from 

 every other genus of fish by the ventrals having an exterior and interior spine 

 which enclose the soft rays between them. It has an unarmed tail, as has also the 

 genus Priodon. Acanthurus has a moveable spine on each side of the tail, which 

 is capable of making a wound like a surgeon's lancet, and some of the species have 

 also a brush of coarse hairs on the forepart of the lateral line. Prionurus and 

 Naseas have fixed cutting laminse on the sides of the tail, and Axinurus has but 

 one of these laminse on each side ; it also differs from the others in its teeth being 

 very slender. Acanthurus hepatus is enumerated by Schoepf among the New 

 York fish. There are some other species in the warmer parts of the Atlantic, 

 but the greater part of the family inhabit the Indian and Pacific oceans. The 

 Acanthurus triostegus, and four others of that genus, were seen at Otaheite by the 

 naturalists of Captain Beechey's expedition. 



