VENTRAL PINS. 21 



some allowance must always be made on this head^ even 

 to the best artists. The more unusual forms of the 

 ventral fin may now be noticed. Sometimes it is 

 single, and merely represented by a prickle^ as in 

 Psettus Sehii, and a large number of the cheloniform 

 fishes (^Balistes Linn.) ; more rarely there are two spines, 

 representing the two anal fins ; for although, strictly 

 speaking, the bony processes in the cheloniform 

 fishes are not real ventrals, yet, as they perform the 

 same office, and are placed in the same situation, we 

 see no reason why they should not be so termed. In 

 the type of the genus Xiphias, or sword-fish, the ven- 

 trals are entirely wanting ; but in the sub-genus His- 

 tiophorus they consist of two slender cirriform filaments, 

 either of equal lengths, as in H, indicus, or with one 

 shorter than the other, as in H. pulchellus. The ma- 

 jority of the GadiadcB, or cods, and of the Blennidce, or 

 blennies, show us an equally slender form of ventrals ; 

 sometimes with a single worm-like ray, forked towards 

 the middle, as in the hakes (^Physis Cuv.) ; and some- 

 times with three, four, or five other rays : yet these 

 latter are generally so diminutive, that they become 

 merely rudimentary. Five soft branched rays, and 

 one spined or stronger one in front of the others, is 

 the usual number seen in the ventrals of ordinary fishes. 

 The most remarkable modification in the form of this 

 fin is seen in the sucking or adhesive fishes, of which 

 there are two distinct groups, both possessing the power 

 of adhering, by this member, to other substances, but 

 very different, not only in their general organisation, 

 but in the structure of those members by which this 

 property is performed. One of these is the family of 

 gobies, GoUadcB ; the other, that of the CyclopterincB, or 

 true suckers : in the first, the two ventral fins are 

 united, so as to form a circular funnel. Upon what oc- 

 casions, however, this instrument of adhesion in the 

 gobies is used, remains at present unknown. Montagu 

 has observed, that in live gobies which he has captured, 

 and put into vessels of water, no instance occurred 



c 3 



