The structures of two newly synthesized endohedral fullerenes, Tm C-3v-C-94 and Ca C-3v-C-94, have been determined by single crystal -ray diffraction on samples cocrystallized with N-II(octaethylporphyrin). Both compounds exhibit the same cage geometry and conform to the isolated pentagon rule (IPR). The metalions within these rather large cages are localized near one end and along the C-3 axis. While the calcium ion is situated over a C-C bond at a 6:6 ring juncton, the thulium ion is positioned above a six-membered ring of the fullerene.