Po rif' e ra, the sponges, distinguished by the canals which perforate the body wall.
Post em bry on' ic, development after birth or hatching.
Pos te' ri or, situated behind or toward the hinder part.
Pro bos' cis, a prolonged, flexible snout or a tubular structure, protruding from the head.
Pro' leg, an unsegmented appendage found in the larvæ of some insects.
Protective resemblance, a method of protection due to the resemblance of an animal to its background.
Pro tho' rax, the most anterior division of the thorax.
Pro' to plasm, the living material composing the cell; the physical basis of life.
Pro to zo' a (sing. protozoön), animals of one cell, existing alone or in loose colonies.
Prox' i mal end, the attached end of anything which has also a free end.