THE REV. R. T. LOWE ON ALEPISAURUS. 399 
front, one twentieth. It is considerably thickened at the base, and not seated in a 
groove. The first three rays are simple, but not pungent, and with difficulty distinguish- 
able ; the remaining eleven branched. Of these eleven, the first two are only bifid, 
and of nearly equal length with the third simple ray, which is the longest ; the three 
next are trifid, but rapidly decrease in length ; the last six are, again, only bifid, of nearly 
equal length, the last four being about the height of the first simple ray, and each more 
remote than the preceding. The first simple ray is not rough. 
The following is the fin formula for the present specimen : 
Ist D. 44. 2ndD.adipose. A.3-+11. P.1+13. V.1+9.C. List, fa Re 
Un. 8+1+8 
Total length, to the tip of the produced upper lobe of the caudal fin extended, 62 inches. 
Greatest depth, being close behind the pectoral fins, 32 inches. 
Greatest thickness, being at the root of the tail or just behind the eyes, 14 inch. 
Weight little more than 4 lbs. 
The lateral line resembles a gelatinous band or ridge, slightly elevated the whole 
length of the body, but most remarkably so, and forming quite a keel, from about the 
middle of the anal fin to the setting on of the caudal. After the fish has been some 
time out of the water, or immersed in spirits, this gelatinous keel falls, and loses nearly 
all its prominency. It is marked by a faint black stripe or line, accompanied by a 
series of pores, set at irregular intervals along each side. Throughout its whole length 
it is nearer the dorsal than the ventral line. The two little accessory oblique ridges on 
each side the termination of the lateral line, at the root of the caudal fin, present in the 
true Mackarels (Scomber vulgaris and Colias), as well as in the Thunnies, are here wanting. 
The base of the first dorsal fin is seated in a deep groove, with jelly-like transparent 
margins. This groove continues backwards, from the termination of the first, nearly 
to the second dorsal fin, becoming gradually more shallow and obsolete. 
The anterior branched rays of the pectoral and ventral fins, and the outer rays of 
both lobes of the caudal fin, have the bars or joints remarkably raised and prominent, 
resembling knobs, or like the knuckles of the fingers. 
The extreme lightness of this fish, in proportion to its size, is equally remarkable 
with its peculiar flaccidity. The head seems ready to separate from the body with the 
smallest force. 
This third specimen was much more brilliantly coloured than either of the former, 
though in a precisely similar manner. On each side, at the origin of the caudai fin, 
was a large metallic iridescent patch of extreme splendour; and the same hues pre- 
vailed, in almost equal brightness, along the base of the anal fin. The iris was coppery 
and golden, the pupil black. 
In my former reference of this new genus to Les Tenioides of Cuvier, I was merely 
guided by its evident affinity to Lepidopus and Trichiurus. ‘These two genera are now 
by Cuvier and Valenciennes, in the eighth volume of their ‘ Histoire’, removed from 
the Tenioides, with which they were associated formerly by Cuvier in his secand or 
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