How many Dragons are there in total in Fairy Tail? Some of the Dragon Slayers were trained by Dragons, while others gained Dragon Slayer Magic by means of Lacrima implants (as in the case of Laxus). For Lacrima implants, the Dragon Slayer Magic has to be extracted from a Dragon (that's my assumption). So how many Dragons in total, living or dead, exist in Fairy Tail? If possible please provide their names.
According to the Fairy Tail wiki, there are 18 Dragons who have been given a name. 


   However in the Grand Magic Games arc we learn that 400 years ago the world was ruled by dragons. Many a Dragon were slain, and thus, the humans became known as Dragon Slayers.


Dragons with titles:


Igneel - The Fire Dragon King
Metalicana - The Iron Dragon
Grandeeney - The Sky Dragon
Acnologia - The Black Dragon (The Black Dragon of the Apocalypse)
Weisslogia - The White Dragon
Skiadrum - The Shadow Dragon
Zirconis - The Jade Dragon
Atlas Flame - The Fire Dragon
Belserion - The Sage Dragon
Irene Belserion - Queen of Dragons
Elefseria - The Law Dragon
Mercuphobia - The Water God Dragon


Other named Dragons:


Motherglare
Scissor Runner
Levia
Dark Dragon
Rock Dragon
Animus