(Chapter 35) Footnote 2:

Lat. solum, perhaps suggested by Galen’s e(/dra, “seat” ( De usu partium 3.93.14): “This tarsus is pierced with fine holes, from which the hairs of the eyelids emerge, the hard tarsus furnishing the foundation [e(/dra] for them and keeping them set upright.” (tr. May 1968, pp. 481f.).