STI & collection_select

I am not understanding how to utilize collection_select with a single
table inheritance model I have been given to use so I hope someone can
tell me what I am not thinking of.

Suppose there is a look-up table called Color (MySQL syntax):

CREATE TABLE Color
( id INT NOT NULL AUTO_INCREMENT,
  CONSTRAINT pk_Color PRIMARY KEY(id),
  INDEX USING BTREE(id),
  name VARCHAR(50) NOT NULL
);

And there is a product, lets use Card:

CREATE TABLE Card
( id INT NOT NULL AUTO_INCREMENT,
  CONSTRAINT pk_Card PRIMARY KEY(id),
  INDEX USING BTREE(id),
  description VARCHAR(100) NOT NULL
);

The table employed in the STI scheme looks like:

CREATE TABLE CardColor
( id INT NOT NULL AUTO_INCREMENT,
  CONSTRAINT pk_CardColor PRIMARY KEY(id),
  INDEX USING BTREE(id),
  type VARCHAR(20) NOT NULL,
  Card_id INT NOT NULL,
  CONSTRAINT fk_CardColor_Card_id FOREIGN KEY (Card_id) REFERENCES
Card(id),
  Color_id INT NOT NULL,
  CONSTRAINT fk_CardColor_Color_id FOREIGN KEY (Color_id) REFERENCES
Color(id)
);

My ActiveRecord models look like:

class Color < ActiveRecord::Base
  set_table_name "Color"
  validates_presence_of :name
  validates_length_of :name, :maximum => 50
end

class CardColor < ActiveRecord::Base
  set_table_name 'CardColor'
  belongs_to :card, :class_name => 'Card'
  belongs_to :color, :class_name => 'Color'
end

class InsideColor < CardColor
end

class OutsideColor < CardColor
end

class Card < ActiveRecord::Base
  set_table_name "Card"
  has_many :insideColors, :class_name => 'InsideColor', :dependent
=> :delete_all
  has_many :outsideColors, :class_name => 'OutsideColor', :dependent
=> :delete_all

  validates_presence_of :description
  validates_length_of :description, :maximum => 100
end

I thought my new.html.erb would employ something like:

<%= collection_select(:card, :insideColor, Color.find(:all, :order
=> :name), :id, :name, { :selected => @card.insideColors.collect {|c|
c.Color_id}}, {:multiple=>true, :size => "3"}) %>

But that yields an error during submit of: InsideColor(#36756150)
expected, got String(#20706320)

How do I go about creating InsideColor objects with the related
selected Color.id's and place them in the association?

Thank you in advance for your time!