uf Whitebait and Shad. 257 



them invariably uniform. Tiie body of the Shad is much 

 deeper in proportion to its length than the Whitebait, its pre- 

 vailing 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 ser- 

 rations on the abdominal edge also differ in shape, as a refer- 

 ence to the accompanying magnified representations will de- 



Abdominal serrated I Abdominal serrated 

 edge of the Shad. [ edge of the Whitebait, 



monstrate. 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 abdo- 

 men in the Shad are lined with a delicate silver-coloured mem- 

 brane 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 resembling the nigrum jpigvientum, not 

 a vestige of which appeal's in the 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 cha- 

 racter. The number of vertebrae in the Shad, of whatever 

 size the specimen may be, is invariably 55 ; the number in the 

 Whitebait is uniformly 56^ and even in a fish of two inches, 

 with the assistance of a lens, this exact number may be di- 

 stinctly made out. 



The value of this character as a specific distinction may be 

 presumed by the following quotation from Dr. Fleming's ex- 

 cellent work on the Philosophy of Zoology, vol. ii. p. 311. 



" The number of the bones of the vertebral colunm in dif- 

 ferent species of fishes, being exceedingly various, suggested 

 to Artedi the use ot this character in the separation of nearly 

 allied species. Among the species of the genus Cj/pTi7ius, for 

 example, a difference in the number of vertebra; has been ob- 

 served to the amount of l^. In ascertaining this character 

 Artedi recommends tlie greatest circumspection. The fish 

 should be boiled, the fleshy parts separated, and the vertcbraj 

 dt:tached from one another, and these counted two or three 

 limes in succession to prevent mistakes. This character is of 

 great use, as it is not liable to variation, individuals of the same 

 species exhibiting the same number of vertebrae in all the stages 

 of llieir growth." 



From the observations made by Mr. Donovan in his History 

 XS. Vol. 6. No. 34. Oc^ 1829. 2L of 



