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208 Hypbridity in Animals. 
Hysrip Rertites, Fisnes, Motiusca ann Insects. 
Among reptiles, I have found but a single authenticated ex- 
ample, that of a cross between the European frog and toad, which 
are generically distinct. (Bufo and Rana. )* 
Among fishes, specific hybrids have been obtained by means 
8 artificial wapeagentinn between Cyprinus carpio, and C. caras- 
s, and between the former species and C. gibellio.t “ Defay 
caioneies a hybrid between the barbus and ale and Blech a 
similar production intermediate between Cyprinus blicco and C. 
Pi 
My friend Mr. 8. 8. Haldeman, well known for his many and 
accurate contributions to various branches of natural science, has 
kindly furnished me with the following note in relation to some 
American freshwater Mollusca, in connexion with the present 
quiry. 
“ Whilst I deem Unio radiatus and U. siliquoideus distinct 
species, there isa 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 
waters of the United States, although I have had many opportu- 
nities for observation. 
“In their proper localities no species can be more readily sepa~ 
rated than Paludina decisa and P. ponderosa ; yet intermediate 
individuals occur which it is extremely difficult if not impossible 
to give an undoubted place with either. This difficulty 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 ~— waters east of the Alleghanies, I could not safely unite 
Perhaps hybridity may be the cause of the aahonity 
where the two species occur in the same locality.” 
In Entomology, Mr. Haworth has published some highly inter- 
esting facts relating to hybrid productions, and particularly in 
respect to the genus Coccinella. Fabricius had noticed and pub- 
lished some of these facts; but Dr. Prichard remarks, that they 
“do not afford an unequivocal example of the union of different 
species, since, according to the opinion of Iliger, accidental varie- 
ties of the Coccinella have been frequently mistaken for distinct 
kinds.”§ Yet on the other hand, Mr. Haworth asserts that he has 
often seen, in coiti, several different species of this genus; and he 
adds the following observations : 
hat they mix sexually with each other, when their proper 
mates cannot be found, is well known; and I have even had 
* Brande’s Dict. of Science, fe. er Prag ie: t Ibid. 
¢ Prichard. Researches, &c., i, p-1 § Ut supra 
