2oG Mr. Yarrell on the supposed Identilij 



But it is not alone on such data as tliese, however conclu- 

 sive they may appear, that I rel}', for the distinction for vv'hich 

 I contend. The best zoologists of the last fifty years have 

 taught us the value as well as the necessity of searching for, and 

 resorting to anatomical distinctions, as the best foundation for 

 the separation of species, and I shall therefore proceed to de- 

 tail the various differences that present themselves on a close 

 examination of the external and internal characters of the 

 Whitebait and Shad, premising, that in every instance I refer 

 to the parts as they appear in a fish of each sort, correspond- 

 ing exactly in size. 



The tongue of the Shad is smooth and dark in colour, the 

 lower jaw has three strong teeth, the whole edge of the upper 

 jaw, which from its shape forms two distinct portions, is also 

 armed with strong teeth, the snout bifid, the eye small. 



The tongue in the Whitebait is rough and white, the lower 

 jaw has no teeth on the outer edge, and differs in its form from 

 the same part in the Shad; the upper jaw in the Whitebait 

 possesses teeth on the lower portion only, the snout is not 

 notched, the eye one third larger than that of the Shad, and 

 there is also an appreciable difference in the form of the oper- 

 culum. Its dorsal line is less curved. 



Edge of the mouth of I Edge of the moutli of the 

 the Shad, magnified. | Whitebait, magnified. 



The dorsal fin of the Shad is placed nearer the head than 

 in the Whitebait, and differs also in being less triangular in 

 its form. The ventral fins of both are placed in a line imme- 

 diately under that of the back. There are also differences in 

 tlie number of fin rays as the following comparative statement 

 will show. 



Whitebait. 

 D. 17., P. 15., V. 7., A. 15. Tail 20. 



Shad, according to Donovan. 

 D. 20., P. 19., V. 12., A. 21. Tail 26. 

 But I place less confidence on these variations in the num- 

 ber of the fin rays, as characters, than on others, not finding 



them 



