subspecies

I believe it [the trilobite Calymene blumenbachii] has been divided into several forms, which cannot claim more than the rank of subspecies, as they pass by slight gradations into forms which no author has yet thought it right to separate from the type species.

But these slight differences will not justify us in considering the West African chiquera as a true species distinct from the Indian true chiquera; it is only a subspecies of the latter true species.

Granular Augite. […] This subspecies of augite has been hitherto found principally in primitive rocks at Arendal in Norway, in several of the iron-mines, particularly that named Ulve-Grube.