The mass spectra of thalmine, thalicberine, and related bisbenzylisoquinoline alkaloids have been analysed and the fragmentation patterns have in part been substantiated by deuteriation experiments. The mass spectra of thalmine and related C(5)-C(7') ether linked alkaloids run parallel to those of the C(8)-C(7') linked types described in Part 1, with intense molecular ions and double benzylic cleavage of the singly and doubly charged molecular ions as the major fragmentation process, but have distinguishing features (e.g., a weak ion (a) from ring F loss, ion (b) (M - 107) from ring E loss with hydrogen transfer, an M - 121 ion (c) from 6-methoxy groups with methyl transfer confirmed by deuteriation). The fragmentation of the base peak ion (d) depends on R1 and R2, assisting in hydroxyl group localization. Double benzylic cleavage of singly charged molecular ions produces ions (f) and (g), which fragment to intense ions (h), (j), (i), and (k) with ratios confirmed by deuteriation. The mass spectra of thalicberine and related C(8)-C(6') linked alkaloids closely resemble the C(8)-C(7') linked types in Part 1 but have weaker ions from ring C/D loss and can be distinguished by methyl transfer. Thalidasine (16) fragments like C(5)-C(7') linked types but shows specific ring E loss without ring F loss or methyl transfer. Cleavage at C-1' is suppressed in alkaloids (17) and (18), which have intense singly and doubly charged molecular ions; the M-1 and M-Me+ ion intensities indicate the 4"-methoxymethyl group is lost from (18).