GREATER SIIL-SMELT. 
915 
they expand in a downward direction so greatly that 
their breadth is about 28 % of their length, which 
measures about 20 — 23 % of that of the head or 28 — 
29 V 2 % °f that of the head reduced. The length of 
the lower jaw is about 8fe- — 8 3 / 4 % of that of the body, 
32- — 34 % of that of the head, or 44 — 48 % of that of 
the head reduced. The dentition of the mouth we 
have already described. The most striking characteristic 
is that, at the extreme front of the palate, the head of 
the vomer and the anterior extremities of the palatine 
bones, which touch the head of the vomer on eaeh 
side, form an arch furnished with a row of small, bent, 
subulate teeth of uniform size. This arch has the ap- 
pearance of an inner upper jaw, compensating the lack 
of teeth on the upper jaw proper. In old specimens 
these teeth are more scattered, but longer and more 
villiform. The teeth on the tongue also seem to become 
more scattered with age: in the semi-elliptical row we 
have counted 10, 8, and 6. There is no palatal fold 
in the usual place, just behind the jaws ; but behind 
the head of the vomer and the incurved ends of the 
palatine bones the skin of the palate lies in a pad-like 
transverse fold. The gill-rakers are set in one row, 
and resemble pointed, rather long, triangular disks, 
which are destitute of the small spines that commonly 
fringe them in the Gwyniads. The pharyngeals are 
armed with several rows of subulate teeth. The pseudo- 
branchim are large. The gill-openings are of consider- 
able size, each extending from the occiput on a level 
with the upper orbital margin and almost in a line 
with the hind margin of the preoperculum down to a 
line with the centre of the eye. The two branchiostegal 
membranes are free both from each other and the 
isthmus. The branchiostegal rays are six in number, 
the last five being sabre-shaped and gradually increas- 
ing backwards both in length and breadth, the first 
narrow and styliform, but curved like the others. 
The dorsal fin is trapezoidal, but its upper posterior 
margin is more or less convex. The first two rays are 
simple; the first branched ray is the longest, being 
twice as long as the first simple ray, but only slightly 
longer than the second. The fin begins at a distance 
from the tip of the snout measuring about 41 or 42 % 
of the length of the body, and the length of the head 
is about 60 or 61 % of the said distance. Its base is 
less in our specimens than 8 % (about 7 3 / 4 %) of the 
length of the body, or about 30 — 32 % of the length 
of the head- Among the preceding members of the 
Salmonoid family the Smelts alone have so short a 
dorsal fin. The greatest height of the fin is about 
twice the length of its base. The anal fin is also tra- 
pezoidal, but lower and at least somewhat longer than 
the dorsal. At its anterior margin there lie three or 
four simple (undivided) rays, the first quite short, about 
half as long as the second, the others gradually in- 
creasing in length to the hindmost, which is about equal 
in length to the first branched (longest) ray, or in other 
words to the base of the dorsal fin. The distance be- 
tween the beginning of the anal tin and the tip of the 
snout is about 78 % of the length of the body, and 
the length of its base is about V 3 (33 — 31 %) of that 
of the head. The adipose fin, which resembles that of 
the Salmons, lies above the 4th — 6th or 5th — 7th 
branched ray in the anal. The caudal is deeply forked, 
the length of its middle rays being only about 1 / 3 of 
that of the longest ones, or about 4 % of that of the 
body. 
The pectoral fins resemble in shape and position 
those of the Gwyniads. Their length is about 14 — 15 
% of that of the body. The first (simple) ray does not 
reach quite to their tip; the second or third branched 
ray is the longest. The blunt ventrals also remind us 
of the Gwyniads, but are distinguished by their nu- 
merous rays — a characteristic generally belonging to 
the lower (earlier) grades of differentiation among the 
Teleosts — and by the covering lobe, formed by large 
scales on the ventral side in front of their base, under 
which they may be concealed to a great extent. Their 
length is about 1 10 — 1 / 9 of that of the body, or 3 / 4 
(78 — 74 %) of that of the pectorals. They are set half- 
way along the body (at a distance from the tip of the 
snout measuring about 49 — 51 % of the length of the 
body), exactly below the termination of the dorsal fin 
or a little farther back. The preabdominal length is 
less than in most other Salmonoids (24 — 26 % of the 
length of the body), but the postabdominal length is 
greater (29 — 27 % of the same). 
The shape and texture of the scales, which are 
rather thick but flexible, vary according to their situa- 
tion. They are densely imbricated, and inserted so far 
into the follicles that most often only 1 4 of their sur- 
face is uncovered by the next scale in front. Their 
exposed part is closely set with small spines, pointing 
in a backward direction, which render the body as 
rough to the touch as in many Sharks. On the other 
hand, this part of the scale is without concentric stria;, 
