Glenn Dallan

I have been looking at the Triads of Ireland and come across the following three wonders.

236. Three wonders of Glenn Dallan s in Tirowen: the boar of Druim Leithe. It was born there, and Finn was unable to do aught against it, until it fell in Mag Li  by a peasant who was kiln-drying. Whence Finn said: " Not well have we fed our hounds, Not well have we driven our horses, Since a little boor from a kiln Has killed the boar of Druim Leithe." 

The Beast of Lettir Dallan. It has a human head and otherwise the shape of a smith's bellows. The waterhorse which lived in the lake by the side of the church cohabited with the daughter of the priest and begot the beast upon her. 
 
The Ox of Dile is the third wonder. Its father came out of the same lake, and went upon one of the cows of the landholder who lived near the church, and begot the ox upon her.

But where is Glenn Dallan?  Does anyone know?