It's a phenomeon we see time and again on title pages. Note that those two names, Louise Jamison and James M. Gleeson, are the same! "Jamison" and "James M." are obviously both James-based. "Louise" and "Gleeson" are both dominated by the "ees" sound. And both last names end in "son." Shift one syllable in the illustrator's name, and you have "Glees James M. Son," which tidily echoes "Louise Jamison." We regularly see collaborator names that mirror one another, as if people choose their workmates based upon such affinities.