Tlachtga and Mogh Ruith
Version 1
Kilbride MS 3, Advocates' Library, Edinburgh

a. Tlachtga can as ro hoinmniged. ní annsa. Tlachtga ingen moga Roith fordosreiblengadar trí meic Símóin druad dia luid le [a] hathair do foglaim druidechta in airther in betha. fo deig is í doróine [ms. doroighne] in roth rámach do Thriun ocus in lia i Forchartha ocus in coire i Cnámchoill. térnái iaram anair ocus in dede sin lé go torracht telaigh Tlachtga. fordoslamnadh ann sin iarum go mberdais trí macu. i. Dorib diatá magh nDoirbi. ocus Cuma diatá mag Cuma. ocus Muach diatá mag Muich. i céin dana beid an anmann sin i cuimni fer nEirenn ní thora dígal nechtrann dochum nEirenn. ocus atbath dia hassaidh ocus is uirri dorinnedh in dún . unde Tlachta. Tlachtga ingen Mogha móir . rosleblengadar meic Símóin ; ó'n nuair thánic dar muir mas . is di atá Tlachtga taebghlas

b. Moghruith .i. Roth mac Righuill ronalt is de ba mogh Ruith. nó mogh roth .i. magus rotarum [ms. rotharam] .i. is a rothaib dognídh a thaisceladh

c. Mogruith mac Cinisc meic Fhirdechet .m. Forgib .m. Firglain .m. Fhírfhalaid .m. Chaeir .m. Fergusa .m. Róig .m. Rosa .m. Rudraige

d. Cacht ingen Chatmainn ben eile d'Fergus máthair Mogaruith meic Fergusa ocus Roth mac Riguill rsnalt. Dér ocus Droigen máthair dá mac Mogaruith .i. Buan ocus Fercorb ocus máthair Chairbri lifechair

Translations:
Tlachtgha whence named? Moghruith [the wizard's] d. Tlachtgha, whom (when with her father she went to study magic in the eastern world) Simon Magus's sons all three had to wife, even she it was that for Trén constructed the roth rámhach, the flagstone that is Forchartha, and the cauldron in Cnámchoill. Then she, bringing with her these two last, returned out ff the E. and reached [the present] tulach Tlachtgha; here she lay in and three sons were born : Dorib, a quo mágh nDoirbi; Cuma, a quo mágh gCuma; Muach, a quo mágh Muaich; so long as which names subsist in the men of Erin's memory, vengeance of outside strangers shall not attain Ireland. She died in childbed and over her the dún was erected, hense Tlachtgha.

b.) Moghruith : either it was Roth mac Rigoll that fostered him, whense magh Ruith "Roth's slave"; or else mogh roth = "magus rotarum," because it was by "wheel-incantation" that he used to make his observations [do his divination]

c.) Moghruith mac Cuinesc's pedigree in six generations to Fergus mac Roich's (or mac Rosa's') s. Ciar : LL.326:5

d.) Cacht, d. of Cahtmann, and another w. to Fergus, was m. of Moghruith mac Fergus; 'twas Roth mac Rigoll that reared him. Dérdroighen was m. of Moghruith's two suons Buan and Fercorb, and m. of Cairbre lifechair.

SOURCE:
Silva Gadelica. trans. and ed. by Standish O'Grady. p 511, III. p48.