148 ACANTHOPTERYGII. TEUTHIDIDiE. > 
In form and general appearance the Spine-tails 
resemble the Chsetodons, with which Linnaeus 
associated them. They are marked by the body , 
being short, and greatly compressed ; it has been ^ 
stated, that the depth of the body, measured 
from the dorsal to the pectoral fins, is always 
equal to, and often exceeds, its length from head 
to tail ; ” but this is certainly not the case with ! 
the most typical forms. There are teeth only h 
in the jaws ; these are trenchant and denticulated, 
like the teeth of a very fine comb : the mouth i 
is small, advanced, but not projectile. The fins j 
are much developed ; they are supported by nu- 
merous slender rays, and are destitute of scales ; 
the dorsal and anal are long ; and the caudal is 
forked, the points frequently being produced into 
filaments. But the most remarkable character 
of these fishes is the presence of moveable spines 
set on each side of the fleshy part of the tail, the ! 
points and edges of which are as sharp as those 
of lancets. With these weapons they inflict dan- 
gerous wounds on the hands of such as handle | 
them incautiously. These lancets have procured I 
for them the familiar name of Doctors,” by j 
which they are generally known to sailors and j 
colonists. I 
Genus Acanthurus^ (Lacep.) i 
The sides of the tail in this genus are armed | 
each with a single lancet only ; the body is oval, I 
covered with minute scales ; the mouth very | 
small and projecting ; the dorsal is long and I 
undivided, supported, as is also the anal, by 
numerous rays, of great slenderness, set very | 
