Columbia subject headings:
Annelida--Embryology.
Arthropoda--Embryology.
Phylogeny.
Harvard subject headings:
Annelida--Embryology.
Annelida--Phylogeny.
Arthropoda--Embryology.
Arthropoda--Phylogeny.
Embryology--Annelida.
Embryology--Arthropoda.
Princeton subject headings:
Annelida--Phylogeny.
Arthropoda--Phylogeny.
Embryology--Annelida.
Embryology--Arthropoda.