398 THE REV. R. T. LOWE ON ALEPISAURUS. 
fragile, not pungent, but flexible like whalebone, curving backwards, rounded, and 
tapering to fine, excessively slender points, like horse-hair, webbed quite up to their 
tips: the web is peculiarly delicate, of extreme tenuity, and inconceivably fragile ; 
coloured dark iridescent steely blue, with a pale azure line extending partly up each 
ray, as in former specimens ; but in this the whole outline is faintly edged with white, 
of which, from their less perfect condition, the traces only were visible in both the for- 
mer individuals. 
The second dorsal fin is just as in the two former specimens. Its hinder edge is 
broad and flattened towards the base, as in the dorsal fins of certain Sharks. Its height 
and breadth at top are each about an inch and a half. 
The most striking and important addition is the correct form of the caudal fin. This 
organ in both the former specimens was too much mutilated to warrant any attempt at 
delineation or description. In the present it is deeply forked, and composed, as in the 
former specimens, of nineteen principal rays, of which ten form the upper and nine the 
lower lobe. Besides these nineteen, there are eight shorter rays, of unequal length, at 
the base of both forks, above and beneath. The great peculiarity which this third speci- 
men has brought to light, is the production of the upper lobe into a long, gracefully- 
arched, linear, or rather tape-like, broad, flattened filament, composed of the one long 
outer unbranched ray, and of three with part of the fourth of the next inner branched 
rays. The first or outermost of the ten rays forming the upper lobe is simple, and ex- 
tends considerably beyond the extreme tip of the lower lobe, but does not reach half the 
length of the produced part of the upper, of which it forms a portion. The next three 
rays are branched, and their threads or branches form entirely, along with the former 
simple ray, the produced or tape-like filament, which is an inch broad at its base, 
slightly narrowing towards the rather obtuse tip to about one third of an inch. There 
are seven threads or branches of these rays, running nearly parallel and reaching to the 
tip. The six next rays are much branched, and gradually shorter ; the uppermost 
thread or branch of the first of them, i.e. of the fifth ray of the upper lobe, is a little 
produced, and forms a part of the base of the lengthened filament. 
The lower lobe of the caudal fin is simple, oblong-oval, acute at the tip. Its lowest 
ray is also its longest, and unbranched. The four next are nearly the same length, and 
branched. The four innermost are gradually shorter, and also branched. 
The upper lobe is between one third and one fourth of the whole length. The lower 
lobe is one tenth of the whole length. 
The middle rays of the caudal fin are faintly barred, but much branched : the outer 
rays are very strongly barred, but gradually less branched from the middle outwards. 
The caudal fin is set on in the peculiar manner general among the Scombride. It 
surrounds the termination of the body on three sides, leaving a rectangular central 
space longer than deep. This peculiarity is chiefly owing to the large number (eight) 
and strength of the supernumerary shorter rays, both above and beneath, which extend 
some distance forwards along the dorsal and the ventral lines. 
The anal fin is one fifteenth of the entire length, and its greatest height, which is in 
