I 



Mr. Yarrell on Whitebait and Shad. 141 



Shad, premising, that in every instance I refer to the parts as they 

 appear in a fish of each sort, corresponding 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 por- 

 tion 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 

 operculum. Its dorsal line is less curved. -" 



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 immediately under that of the 

 back. There are also differences in the number of fin rays as the follow- 

 ing comparative statement will shew. 



WhitehaiL 

 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 number of the 

 fin rays, as characters, than on others, not finding them invariably uni- 

 form. The body of the Shad is much deeper in proportion to its length 

 than the Whitebait, its prevailing colour on the back, blue, without, any 

 very apparent lateral line. The colour of the back of the Whitebait 

 is greenish ash, the lateral line impressed, distinct and straight. The 

 serrations on the abdominal edge also differ in shape, as a reference to 

 the accompanying magnified representations will demonstrate. The form 

 of the stomach is similar in both these fishes, as might be expected from 

 their belonging to the same genus, but the caecal appendages are much 

 more numerous in the Shad than in the Whitebait. The parietes of the 

 abdomen in the Shad are lined with a delicate silver coloured membrane 

 which also exists in the Whitebait, but in the latter fish this membrane is 

 covered on the side next the viscera with a dark colouring matter resem- 

 bling the nigrum pigmentum, not a vestige of which appears in the Shad. 



