MR. W. THOMPSON ON A NEW SUB-GENUS OF FISHES. 211 
some respects, having but one spinous ray, and that in the ventral fin. At the sug- 
gestion of John Edward Gray, Esq. F.R.S., I have, however, reconsidered the subject, 
and have come to the conclusion above advanced. 
As a difference of opinion may still exist with regard to the position of this genus, I 
subjoin the observations originally made. 
Like certain other genera which are comprehended under Acanthopterygii, the first 
order of the Osseous Fishes, its fins are altogether destitute of spinous rays, but like 
those alluded to, such as Zoarces, &c., its other characters’ seem to point out the Teni- 
oides as the family to which it belongs. Of the eight® genera of Tenioides already 
known, viz. Lepidopus, Trichiurus, Gymnetrus, Stylephorus, Cepola, Lophotes, Trachypte- 
rus, and Alepisaurus*, the specimen under consideration agrees with Trichiurus and 
Stylephorus in being apodal, or wanting ventral fins, but in this character only is there 
any generic accordance. Though considerably more elongated, from the head poste- 
riorly it approaches most nearly to Cepola rubescens in the form of the body and in the 
forward commencement of the anal fin, which, with the dorsal, is prolonged until it joins 
the caudal; but it is only in the continuity of these fins until this junction is effected 
that the resemblance holds, as in my specimen the dorsal rays (of which the five fore- 
most are very short) increase in length posteriorly, and near the caudal fin are about 
three times as long as the depth of the body beneath them ; in the anal fin, which is 
throughout much higher than the dorsal, the rays likewise increase posteriorly, and 
near the caudal are in length four times greater than the depth of the body at the same 
place. The length of the posterior rays of these fins causes the dorsal, anal, and caudal 
to appear as one, whilst, though they do join in Cepola rubescens, the last ray of the 
dorsal and anal being much shorter than the outer rays of the caudal, may at the same 
time be said to mark distinctly the termination of each fin*. In my specimen the anal 
originates two lines in advance of the dorsal fin. 
In the form of the head and in dentition, it differs so remarkably from all the other 
genera as to render a comparison with them unnecessary. Its absolute characters must 
suffice for distinction. 
As Mr. Yarrell has in his valuable work on “ British Fishes” (vol. i. p. 185.) sug- 
gested, that of the two specimens described as Trichiuri by Mr. Hoy in the Linnean 
Transactions (vol. xi. p. 210.), the first may be the type of a new genus, it should be 
observed, that this individual approximates the specimen under consideration in but one 
generic, and that a negative character, namely, the want of ventral fins. 
' I allude to external characters only, being unwilling to dissect a specimen as yet unique. 
2 For the purpose of comparison, all the genera given by Cuvier in the ‘‘Régne Animal” and ‘Hist. de Poiss.”” 
are here brought together. ’ Zool. Trans. vol. i. p. 123. 
+ For illustration of this, see Cuv. and Val. Hist. de Poiss. pl. 300. Two species of Cepola from Japan, the 
C. limbata and C. marginata, are (as has been observed in this work, tome x. p. 403.) figured by Krusenstern 
with the caudal fin continuous with the dorsal and anal, as in the genus Anguilla. 
