Prof. Robert Mathiesen has called my attention concerning lect 315: It is in the Josiah Catalog at Brown University Library (please see link below). It has never been scanned, according to Prof. Mathiesen. Kind regards.
http://josiah.brown.edu/search~S7?/Xeuchologion&searchscope=7&SORT=D/Xeuchologion&searchscope=7&SORT=D&searchscope=07&SUBKEY=euchologion/1%2C20%2C20%2CB/frameset&FF=Xeuchologion&searchscope=7&SORT=D&3%2C3%2C