Pagurus Pagurus Pagurus is a genus of hermit crabs in the family Paguridae. Like other hermit crabs, their abdomen is not calcified and they use snail shells as portable homes. These marine decapod crustaceans are omnivorous, but mostly prey on small animals and scavenge carrion. "Trigonocheirus" and "Pagurixus" used to be considered subgenera of "Pagurus", but the former is nowadays included in "Orthopagurus", while the latter has been separated as a distinct genus. Some 170 species are presently placed in "Pagurus"; many others have been placed here at one time or another but are now assigned to other genera of Paguroidea.
On the Origin of Species an incipient species" and that "species are only strongly marked and permanent varieties". He argues for the ubiquity of variation in nature. Historians have noted that naturalists had long been aware that the individuals of a species differed from one another, but had generally considered such variations to be limited and unimportant deviations from the archetype of each species, that archetype being a fixed ideal in the mind of God. Darwin and Wallace made variation among individuals of the same species central to understanding the natural world. In Chapter III, Darwin asks how varieties "which I have called incipient species"