19763

If membership in a species is characterized by the inability to breed with members of another species, how can there be “animal species known to have arisen from crossbreeding with other species?

Jeffry D. Mueller
Eldersburg, Md.

Exceptions happen. Also, biologists argue about what defines a species. —S. Milius I suggest that the new species be named Lycaeides lolita , in honor of Vladimir Nabokov.

Joseph Singer
Fairfax, Va.