130 
J. R. AUDY 
The major types of seta are first picked out, measured, and sketched as shown in Fig. 1. 
These setae are generally of the following types: ( a ) Ordinary barbed or pectinate setae (the 
others presumably being specialised sensory setae of various sorts). ( b ) Blunt striated setae 
(“ B ”), which are typical solenidia and similar to the tarsal spurs of the larvae, (c) Pointed 
striated setae (“ P ”), similar to the pointed tibialae and genualae of larvae, and obviously of 
the same type as the blunt setae. ( d ) Tapering setae (“ T ”), slender and usually obviously 
distinct from the pointed solenidia; these setae appear not to be striated but this requires 
closer study, (e) Recurved setae (“ R ”), relatively short, sharp-pointed, and recurved towards 
the proximal part of the leg; apparently striated. (/) Microsetae ( ‘V ”). 
One or more distinct representatives of each of these types may be found in a given species, 
and may be given designations, e.g., LB, MB, FB for long, medium-length, and thick flask- 
shaped solenidia, or BN for a narrow cylindrical one. The species of nymphs which have so 
far been examined usually have 6 to 10 distinct setae. As we have already noted, it is important 
that these be sought out, measured, sketched to scale, and given some sort of letter- designation 
at the outset. This takes a surprisingly short time. 
The next stage is the enumeration and tabulation of the setae, type by type and segment 
by segment (Table I). It needs very little practice for this to be done quickly. Individual 
workers will prefer their own systems, but the writer has now come to prefer tabulating the 
pointed (P, R, ^ ), blunt (B), and tapering (T) setae in three columns, using the following small 
letters to suggest roughly the main distribution of the setae on the segment concerned : 
d, dorsal aspect. p, proximal, 
v, ventral aspect. s, distal. 
l, lateral (or posterior) aspect. t, terminal, e.g., near tarsal claw. 
m, medial (or anterior) aspect. 
Table i. 
Example of tabulation of setae on legs of a nymph. 
Segment. 
Euschongastia species in 
Pointed strong 
MS, rawz-group (Fig. 1). 
Blunt fingerlike 
Fine tapering 
setae (P). 
setae (B). 
setae (T). 
Tarsus I 
;jl (mid-dorsal) ... 
10 (8d, m.l.) ... 
— 
lit (4tm, 4tl in vertical rows)... 
6oRv (approx, in 9 rows) 
9M (8s, lp, more slender 
proximally) 
2-3S (l,lv) 
— 
Tibia I 
fitl. 2Rt (d.m) 
22 (distal 2/3, dt) 
16 (prox 2/3 ; 6d) 
Genu I... 
[JLSt 
3 (2l, tm) 
20s 
Telofemur I ... 
t 
— 
— 
Tarsus II 
Rti (terminala) [as (prox. to MB) 
M(t) S(p) (not thick)... 
— 
Tibia II 
— 
SNt 
1-2 (p.s) 
Genu II 
— 
— 
3 s (ipd) 
Telofemur II ... 
(t) 
— 
— 
Tarsus III 
M (st; 15(a) 
s (prox. to MB) 
Tibia III 
— 
MNtm 
5 (dt, 2d, 2ps) 
Genu III 
— 
— 
2d (tandem) 
Telofemur III 
t 
— 
— 
Tarsus IV 
Rtl 
M (prox to LT) 
2 (p, & t to MB) 
Tibia IV 
Rt 
— 
7 (5p in group) 
Genu IV 
— 
— 
5 ( 4 s 3 P) 
Telofemur IV 
— 
— 
A meticulous study of the leg chaetotaxy is necessary. This would best be made as a 
comparative study with the Trombidiidae and related prostigmatic mites. The development 
of the specialised setae from nymphal to adult stages of the Trombiculidae is also of great 
interest. The excellent studies made by Grandjean (1943, x 947 ) ma Y be taken as a model. 
STUD. INST. MED. RES. 
