FORM, COVERING, ETC. OF FISHES. 319 



fishes; some are round, some oval, others are 

 angular, and others are denticulated. They en- 

 velop the body so completely as to protect every 

 part of it, and at the same time admit of that 

 perfect flexibility which is requisite to those rapid 

 and graceful motions for which the finny tribes 

 are so remarkable. Among evidences of design 

 the structure of the scales of fishes merits our 

 careful attention. On examining them with 

 a microscope, it is found that each of these 

 organs is pierced by a minute hole, which is the 

 extremity of a tube. Through this orifice is 

 emitted a kind of mucus or slime, which is se- 

 creted by glands, and forms an external coating, 

 which not only lubricates the body of the animal, 

 but diminishes the friction of its transit through 

 the water. The orifices are found to be more 

 numerous and larger about the head of the fish 

 than the other parts of its body, and in this we 

 perceive an additional evidence of creative fore- 

 sight acting in correspondence with the laws of 

 physics ; for, as Mr. Yarrell has observed, " whether 

 the fish inhabits the stream or the lake, the 

 current of the water in the one instance, or pro- 

 gression through it in the other, carries this de- 

 fensive secretion backwards, and spreads it over 

 the whole surface of the body." This provision 

 is, as our readers will observe, analogous to that 

 which is found in the structure of birds, in which 

 a gland is made to supply the oily matter by 

 which the feathers are smoothed and rendered 

 impervious to moisture. We thus perceive, in. 



