Nau´ti-lus [Gr. nautilos, sailor.] A cephalopod.
Nem-a-thel-min´thes [Gr. nema, thread; helmins, worm.]
Nem-er-ti´na [Gr. nemertes, unerring.] Worms with skin ciliated, proboscis retractile, and nervous, muscular, and vascular systems characteristically developed.
Ne-o-lith´ic [Gr. neos, new; lithos, stone.]
Noc-ti-lu´ca mi-li-a´ris [Lat. nox, night; luceo, shine; miliarius, < milium, millet.]
No´to-chord [Gr. notos, the back; chorda, a chord.] A cartilaginous rod found in the young chordate embryo in a situation that is later on occupied by the centers of the bodies of the vertebræ. It separates a dorsal nervous system from a ventral alimentary (digestive) canal. The notochord is persistent in its entirety in Leptocardians and Marsipobranchs and also in some pisces, as the sturgeon.
O-don-tor´ni-thes [Gr. odous, a tooth; ornis, bird.] Including all those extinct birds having teeth.
Œ-soph´a-gus [Gr. oiso, will bear; phagein, eat.] The gullet; the membranous tube through which food passes from the pharynx to the stomach.
On-tog´e-ny [Gr. on, being; genesis, origin.] The history of the evolution of the individual; the development of the individual.
On-to-ge-net´ic [Gr. on, being; genesis, origin.] Pertaining to ontogeny.