104 
ICHTHYOLOGY 
ACRONURUS FORMOSUS. 
The genus Acronurus of Guntlier is particularly distin- 
guished from Acmthurus, by the absence of scales, and by 
the skin of the body being covered with very fine vertical 
striae. 
The four known sorts included in this division are all from 
the Indian Ocean ; several of the species present the same 
disposition of colours we have to record here, but the propor- 
tions of the body do not allow this species to be placed with 
either, except Melanurus, of which it is easily distinguishable. 
Height of body being three-fifths of the length without the 
caudal fin, or once and eight-tenths of the total length. 
The head is contained three times and one-third in the same, 
and the eye twice and two-thirds in the head. 
The body is very compressed, forming a broad oval ; the 
anterior profile of the head is convex ; the crest over the orbit 
is serrated; the lateral line is elevated, forming a ridge 
sinuous and curbed strongly downwards towards the end on 
the dorsal, to arch a little over the caudal spine ; it extends to 
the base of the caudal in running a little lower than the 
middle of the tail ; on this last part the fine transverse ridges 
take the form of regular scales ; the movable spine is rather 
arched. 
The dorsal has nine spines, the first of which is short and 
the second much broader than all the others, and sulcated in 
the middle ; they are all of about the same length except the 
first ; the soft rays number thirty ; the caudal is bifurcated ; 
it is formed of sixteen long rays and qf several short ones on 
each side ; the anal is formed of three spines and of twenty- 
seven rays ; the first spine is large, broad, and arched, and 
presents the same sulcated appearance as the second of the 
dorsal. The ventrals have a strong spine and six rays ; the 
pectorals are as long as the head, formed of one very short 
and of another long simple ray and of fourteen branched ones. 
The colour, after preservation in spirits, is of a fine reddish 
brown ; with all the anterior part, comprising the head and 
all the portion extending to behind the insertion of the 
pectorals, of a fine golden colour ; the fins are similar ; the 
