def __init__(self, session=None):

		# Create class registry for SA_DAO parent class.
		class_registry = {}
		for clazz in [Habitat, Substrate, Feature, Habitat_Type]:
			class_registry[clazz.__name__] = clazz

		SA_DAO.__init__(self, session, primary_class=Habitat, class_registry=class_registry)
	def __init__(self, session=None):

		# Create class registry for SA_DAO parent class.
		class_registry = {}
		for clazz in [Cell]:
			class_registry[clazz.__name__] = clazz

		SA_DAO.__init__(self, session, primary_class=Cell, class_registry=class_registry)