142 Mr. Yarrell on Whitebait and Shad. 



There is also another difference between the Shad and the Whitebait 

 upon which I place greater reliance, in proof of specific distinction, than 

 on any other single anatomical character. The number of vertebrae in the 

 Shad, of whatever size the specimen maybe, is invariably 55; the 

 number in the Whitebait is imiformly 56, and even in a fish of two 

 inches, with the assistance of a lens, this exact number may be distinctly 

 made out. 



The value of this character as a specific distinction may be presumed 

 by the following quotation from Dr. Fleming's excellent work on the 

 Philosophy of Zoology, vol. II. page 311. 



" The number of the bones of the vertebral colunm in different species 

 " of fishes, being exceedingly various, suggested to Artedi the use of this 

 *' character in the separation of nearly allied species. Among the species 

 " of the genus cyprinics, for example, a difference in the number of 

 " vertebrae has been observed to the amount of 14. In ascertaining this 

 ** character Artedi recommends the greatest circumspection. The 

 " fish should be boiled, the fleshy parts separated, and the vertebrae de- 

 *' tached from one another, and these counted two or three times in 

 " succession to prevent mistakes. This character is of great use, as it is 

 " notUableto variation,- individuals of the same species exhibiting the 

 " same number of vertebrae in all the stages of their growth.'* 



From the observations made by Mr. Donovan in his History of British 

 Fishes, it would be inferred, that the Shads visiting the Thames in the 

 months of May and June, and appearing in immense quantities, heavy 

 in roe, about Greenwich and Blackw all, there deposit their ova, which 

 on vivification become the well known Whitebait. It seems not to be 

 generally known that the Whitebait, though often caught as high up 

 the river as Blackwall, are as frequently taken as low down the river as 

 Erith. 



The situation they are found in by the fishermen depends entirely on 

 the state of the water. Always occupying a station which affords a mix- 

 ture of the water of the sea and river, they are a salt-water fish rather 

 than otherwise, coming upwards with the first part of every flood-tide, 

 swimming always near the surface, avoiding the strong current, preferring 

 the slack water at the sides of the stream that they may not be carried 

 too far up, and returning towards the sea with the first of the ebb-tide. 



