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Plate IV. Surface sensilla on the antennae of the blowfly. 



Fig. 1 . Transverse section through the base of a thick-walled sensillum showing 



a bipartite scolopoid sheath ( x 28,000). 

 Fig. 2. Transverse section through the base of a thick-walled sensillum showing 



a tripartite scolopoid sheath ( x 56,000). 

 Fig. 3. Transverse section through the base of a thick-walled sensillum showing 



a unitary scolopoid sheath ( < 39,200). 



Fig. 4. Transverse section through the base of a thick-walled sensillum showing 



a quadripartite scolopoid sheath ( :■: 49,000). 



Fig. 5. Transverse section through a stellate sensillum ( ; 56,000). 



