FIN

(Lat. finna.) A flattened expanded organ, projecting from the body, and serving as an instrument of locomotion in water. Many species of the whale tribe po e an immoveable fin upon the back, composed merely of a reflection of integument over a ma of dense and ligamentous cellular membrane; the tail fin in the same order has a similar structure, but is moved by the action of the muscles upon the caudal vertebrae, which are continued through the middle {jart. The anterior fins, corresponding to the pectorals in fish, are susceptible of greater variety of motion, from being supported by a series of bones corresponding to those of the fore extremity of other mammal i a. In fishes the fins are supported by elongated filamentary bones or rays, the nature and number of which afford the zoologists important characters for distinguishing the different groups; and in works of Iclithyology a system of notation is employed, which briefly but clearly expre es these characters. Thus the formula of the number of fin-rays in the perch is thus expre ed: — D. 15, 1 -J- 13; P. 14; V. 1 + 5; A. 2 + 8; C. 17. Which signifies that D., the dorsal fin, has in the first fin 15 rays, all spinous or bony; in the second fin, 1 spinous plus 13 that are soft. P., pectoral fin, 14 rays, all soft, v., the ventral fin, with I spinous ray plus 5 that are soft. A., the aural fin, with 2 spinous rays plus 8 that are soft. C, the tail or caudal fin, 17 rays. In enumerating the rays, those only which extend from the longest ray in the upper portion to the longest ray in the lower portion, both inclusive, are counted. FINALE.. (It.) In Music, the last of a series of movements in a composition; also the closing scene of each act of an opera buffa. [s. 464]