i 



Dr Morton on Hybrid Animals and Plants. 283 



Among fishes, specific hybrids have been obtained by means 

 of artificial impregnation between Cyprinus carpio and 0. ca- 

 rassias, and between the former species and C. gibellio.* " De- 

 fay mentions a hybrid between the bar bus and carpio, ftiid 

 Bloch a similar production intermediate between Cyprinus 

 blicco and C. brama.^'] 



My friend Mr S, S. Haldeman, well known for his many 

 and accurate contributions to various branches of natural 

 Science, has kindly furnished me with the following note ill 

 relation to some American freshwater Mollusca, in connexioii 

 with the present enquiry. 



" Whilst I deem Unio radiatus and U. siliqtioideus distinct 

 species, there is a certain variety, apparently of the latter, 

 although almost precisely intermediate, which induces me to 

 believe it may possibly be a hybrid. I have never, however, 

 seen any thing like a hybrid between the other species inhabit- 

 ing the eastern waters of the United States, although I have 

 had many opportunities for observation. 



" In their proper localities, no species can be more readily 

 separated than Pahidina decisa and P. ponder osa ; yet inter- 

 mediate individuals occur, which it is extremely difficult if not 

 impossible to give an undoubted place with either. This dif- 

 ficulty has sometimes almost induced me to regard the two 

 as one species ; but when I found that the best developed 

 specimens of P. decisa never take the form of P. ponderosa 

 where the latter is not found, as in the waters east of the 

 Alleghanies, I could not safely unite them. Perhaps hybridity 

 may be the cause of the difficulty where the two species occur 

 in the same locality." 



In Entomology, Mr Haworth has published some highly 

 interesting facts relating to hybrid productions, and particu- 

 larly in respect to the genus Coccinella. Fabricius had 

 noticed and published some of these facts ; but Dr Prichard 

 remarks, that they " do not afford an equivocal example of 

 the union of different species, since, according to the opinion 

 of Illiger, accidental variieties of the Coccinella have been fre- 



* Brande's Diet, of Science, &c., Art. Hybrid. 

 t Prichard. Researches, &c., i, p. 140. 



