I have uploaded
to the LexiLine files on Ancient Ireland.
Fenegh Beg again shows that we pay too little attention to the shape of the capstones on dolmens, since these capstones are often in the shape of the constellation of stars they represent or the object represented, so also here, where the Fenegh Beg capstone is in the shape of Boötes.
As a matter of etymology, Fenagh (Fe-NAGH) in Leitrim = Boötes = could be related to Arabic NAKKAR "Boötes". FENAGH may just mean the Boötes shape of "FINGER" based on Indo-European e.g. Latvian NAG- "nail", so that you have the Latvian variant PIE-NAGA meaning "at the nail" = Finger in this sense but also the Latvian PIE-ROKAS "at the hand" = Latvian PIRKSTS < PIRKS-TAS "finger".
This would indicate the finger was originally divided in conception at the joints - which is logical. You have the nail, the finger part next to the nail, the finger part next to the hand, and then the hand to the wrist, then the arm to the elbow, the elbow to the shoulder, etc., divisions confirmed by ancient measurement units.