Unlike the majority of science fiction (and fantasy) magazines of the 40s and 50s, The Magazine of Fantasy and Science Fiction eschewed interior art. The issue of September, 1956 was an exception to this policy, featuring two illustrations – below – by Frank Kelly Freas, which accompanied Poul Anderson’s tale “Operation Afreet”.
The third illustration is an allegorical image created by the unknown artist “H.M.”
(Page 11) 
(Page 37)
(Page 37)
The cover and story depicted are from the September 1956 issue of the Magazine of Fantasy and Science Fiction rather than the 1955 issue. This can be confirmed by examination of the issues on the Luminist website among others.