1949 ] Dinnih and Zumpt — Rhipicephalince 5 
sory organ, because a tuft-sbaped structure is its most 
striking characteristic. In the adult tick be described 
this organ as follows in side view (PI. 1, fig. 2) : “The 
distal portion of the chitinized passage or lumen appears 
arrow-shaped. Below this lies a narrow pagoda-shaped 
4 tuft’ chamber and farther inside a small, more or less 
spheroidal 'terminal chamber.’ This is separated from 
cephalus appendiculatus Neum. B, Same in the larva. C, Same 
in the nymph. D, Sensillum hastiforme of Rliipicep'halus appendi- 
culatus Neum. E, Same in the nymph. F, Same in the adult 
female. 
the middle chamber by projecting ledges which leave 
room only for a small circular opening. The innermost 
chamber is attached to a simple duct into which the glan- 
dular cells extend, enveloping the nerve cells. The sur- 
rounding chitin is especially thick beneath the lower por- 
tion of the 'arrow points.’ The nerve cells decrease in 
size as they enter the 'terminal chamber.’ The axial 
fiber is attached to a strong scolopale which enlarges to> 
