226 Professor Owen's Teleology of the Skeleton of Fishes. 



legs are the sole terrestrial locomotive organs in birds, whose fore- 

 limbs are exclusively modified, as wings, for motion in another ele- 

 ment. The legs are the sole organ of support and progression in 

 Man, whose pectoral members or arms are liberated from that office, 

 and made entirely subservient to the varied purposes to which an 

 inventive faculty and an intelligent will would apply them. To what 

 purpose, then, encumber a creature always floating in a medium of 

 nearly the same specific gravity as itself, with hind-limbs % They 

 could be of no use : nay, to creatures that can only attain their prey, 

 or escape their enemy, by vigorous alternate strokes of the hind 

 part of the trunk, the attachment there of long flexible limbs would 

 be a grievous hinderance, a very monstrosity. So, therefore, we 

 find the all-wise Creator has restricted the development and connec- 

 tions of the hind-limbs of Fishes to the dimensions, and to the form, 

 which, whilst suited to the limited functions they are capable of in 

 this class, would prevent their interfering with the action of more 

 important parts of the locomotive machinery. 



In most fishes the ventral fins merely combine with the pectoral 

 fins in raising, and in preventing, as outriggers, the rolling of the 

 body ; but some very interesting modifications of the ventral fins in 

 relation to particular habits of certain species, may be noticed. In the 

 Blennies, the Forked Hake (Phycis^, the Forked beard (Raniceps), 

 and some other fishes, the ventral fins are reduced to filamentary 

 feelers. In the Lump-suckers (Cyclo'pterus), the ventrals unite to- 

 gether, and combine with part of the pectorals to form a sucking disc 

 or organ of adhesion below the head, just as the opercular and bran- 

 chiostegal fins are united together to form the gill-cover. In the 

 long-bodied and small-headed abdominal fishes, the ventrals are situ- 

 ated near the anus, where they best subserve the office of accessory 

 balancers ; in the large-headed thoracic and jugular fishes, the loose 

 suspension of these fins, and the absence of any connection with a 

 sacral part of the vertebral column, permits their transference for- 

 wards to aid the pectoral fins in raising the head. 



The following short account of some experiments upon fish, made 

 for the purpose of ascertaining the use of their fins, I give in the 

 words of their gifted describer Paley, to whom comparative physiology 

 owes many beautiful accessions to its teleological applications. 



" In most fish, beside the great fin — the tail, we find two pairs of 

 fins upon the sides, two single fins upon the back, and one upon the 

 belly, or rather upon the belly and the tail. The balancing use of 

 these organs is proved in this manner : Of the large-headed fish, if 

 you cut off the pectoral fins, that is, the pair which lie close behind 

 the pectoral gills, the head falls prone to the bottom ; if the right 

 pectoral fin only be cut off", the fish leans to that side ; if the ven- 

 tral fin on the same side be cut away, then it loses its equilibrium 

 entirely ; if the dorsal and anal fins be cut off, the fish reels to the 

 right and left ; when the fish dies, that is, when the fins cease to 



