Foot & Strobell. 



BIOL. BULL. VOL. XXXII. PI. 3. 



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K.F. & E.C.S. photo 



INTROMITTENT ORGANS of the offspring from the BACK-CROSS, Fi 9 (from E. VARI- 

 OLARIUS X E. ICTERICUS) by E. ICTERICUS. 



