76 
structure of those of Scarus, being composed of a multitude of mi- 
nute teeth, arranged in a quincuncial order in many rows, and so in- 
corporated with the bone that they produce no inequality of surface, 
but reflect the light in certain positions so as to reveal their struc- 
ture. The two premaxillaries conjointly, and the two halves of the 
mandible, resemble half the bowl of a spoon with straight cutting edges, 
which under a lens appear to be striated and minutely crenulated. 
At the symphysis of the mandible, the cutting edge rises slightly, so 
as to seem very slightly peaked. The orifice of the mouth is com- 
paratively small, and the small maxillaries are concealed under the 
skin at its corners. Interiorly there is a conspicuous velum in both 
jaws. ‘The small nostrils lie in a membranous space above the pre- 
orbitar. 
The entire head is covered with smooth integument, which has no 
inflexed folds at the edges of the opercular pieces or preorbitar, but 
is continuous with single lips, that are capable of covering the jaws. 
The gill-membrane is continuous with the edges of the interopercula, 
and passes over the isthmus to which it is partially adherent, leaving 
a small flap posteriorly. It is sustained by four flat thin rays on each 
side. In length the head is equal to five diameters and a half of the 
circular orbit, and the space between the eye and the tip of the gill- 
flap equals three of these diameters. The eye is near, but does not 
touch the upper profile of the head. A triangular preorbitar, having 
a length equal to the diameter of the orbit, is so concealed by the in- 
tegument that it is scarcely discernible in the recent fish, but in the 
dried specimen it shows a slightly raised disk bounded in a somewhat 
radiated manner by slightly prominent mucous canals. The rest of 
the suborbitar chain goes round more than half the orbit in form of 
a slender line of simple mucous tubes. The two limbs of the pre- 
operculum, equal to each other in length, meet at a right angle and 
inclose a broad and perfectly smooth cheek. In the dried fish the 
disk of the bone appears raised, and is edged irregularly with mucous 
prominences, but the under border of the bone is thin, and is scarcely 
distinguishable from the very thin, flexible interoperculum. At the 
temporal angle of the gill-plate there originates a bushy cluster of 
prominent ramifications, which disappear about the middle of the 
disk, and are most probably not visible at all in the recent fish. The 
rather narrow, very thin suboperculum is lengthened into the tip of 
the gill-cover, in which the flexible bone is scarcely to be distinguished 
from the membrane. The gill-opening is restricted above, the whole 
upper edge of the operculum being attached to the side of the head 
by membrane. Posteriorly and above the pectoral the gill-membrane 
is vertically truncated, and the gill-opening slopes from the level of 
the upper ray of that fin downwards and forwards till it terminates 
opposite to the angle of the preoperculum. A row of small scales 
exists on the suprascapular region, but there are no other scales, 
nor any bony or spinous points on the head. 
The scales are cycloid and of smaller size than those of Scarus, 
there being forty-eight in a longitudinal row between the gill-opening 
