6 
Psyche 
[Mar. 
form a knot and then tapers down, becoming pointed 
again upon entering the ‘ pagoda-shaped chamber’ in 
which the ‘tuft’ is located. This tuft has much the 
shape of a gas flame and is not chitinized but of a uni- 
form structure, although at times it seems to be some- 
what fibrillar.” 
The larvae we examined all show, contrary to Delpy’s 
description, four pairs of spiracle-like structures, three 
of them behind the coxae, the fourth on the opisthosoma 
(PL 2, figs. 4 and 5). A comparison of their inner 
structure (Text-fig. 1A-C) with P. Schulze’s description 
and drawings clearly shows that these so-called “larval 
spiracles” are in reality sensilla sagittiformia. The finer 
structure of the organ is best seen in the opisthosomal 
pair of the larvae of Rhipicephalus appendiculatus and 
Boophilus calcaratus. It is pear-shaped and pierces 
with its conical end the integument on the dorsal face of 
the fourth festoon. The walls are of thick chitin, the 
chitinous capsule being 0.012 to 0.016 mm. long and 0.011 
to 0.014 mm. broad. A funnel-shaped fold is visible 
within the capsule. The narrow ends of this capsule, 
pointing toward the opening, are less strongly chitinized 
and look in direct view like a pair of lips lying within the 
capsule (compare PI. 1, fig. 1). Within these lips lies 
the tuft-like structure, surrounded by a fine pagoda-like 
contour. 
The sensilla sagittiformia behind the second and third 
coxae are very similar in structure to the opisthosomal 
pair described above. On the other hand, the pair lo- 
cated behind the first coxae at the edge of the scutum 
seems to have a strikingly thick-walled capsule which is 
fully embedded in the chitin of the scutum. It is 0.019 
to 0.022 mm. long, 0.016 to 0.022 mm. wide at the base, 
with the opening 0.011 to 0.014 mm. in diameter. The 
“tuft” is difficult to recognize here, but is shaped as in 
the other pairs. 
2. Sensilla hastiformia (spear-shaped organs) 
The sensilla hastiformia, as described by P. Schulze 
for the adult ticks, are much smaller than the arrow- 
