Dr. Harrison Allen spoke of the disposition occasionally exhibited in adult mammals, for the proportions of different parts of the body to remain as they were in the immature individuals. He claimed for this peculiarity that it is not due to arrest of growth but to the fact that certain parts preserve the peculiarities of the young; thus, for example, among the bats, the so-called species V. lucifugus exhibits a number of characteristics which are found in the immature animal and which are the same in kind as those that exist in an individual which in every other respect answers to the description of the adult. In young bats, the foot and thumb are apt to be large as compared with the same parts in the adult, at the same time that the auricle and tragus are correspondingly small and the snout high, blunt and nearly naked. The parts often so remain. Dr. Allen proposed for this peculiarity the term pedomorphism.
Allen, H. (1891). Pedomorphism. Proc. Acad. Nat. Sci. Philadelphia 1891, 208-209: 208.