O' va ry, the organ in which the egg cells are developed.
O vi pos' i tors, organs used to deposit eggs.
Pal' li al, a line connecting the two muscle scars in a bivalve shell.
Palp, (1) a jointed finger-like structure on the oral appendages of arthropods; (2) oral appendages found in mollusca.
Pan' cre as, one of the glands of the digestive system.
Par a nu' cle us, see Nucleolus.
Par' a si tism, an association of two animals, one living at the expense of the other.
Pec' to ral, (1) pertaining to the thorax or breast; (2) the anterior of the paired fins of fishes.
Pelvic, (1) pertaining to the pelvis; (2) the posterior paired fins of fishes.
Pen, a remnant of exoskeleton found in the squid.