Johnstonianidae — Newell 
453 
on all segments of all legs beyond the basi- 
femur, none ventral, except on the tarsi. Ves- 
tigial setae present only on patella I and II 
and tibia I. Famulus of tarsus I at 0.55 pd, 
famulus 2 at 0.62 to 0.79 (this variation was 
noted on the right and left sides of a single 
male). Eupathidia of tarsus I extending from 
0.17^ to 0.17V, claw fossa absent. Eupathidia 
of tarsus II extending from 0.43V to 0.97^; 
tarsus tapering rapidly beyond 0.75V, but no 
true claw fossa present. Tarsus III with eupa- 
thidia at 0.41V, 0.64/?, and 0.9 6pv; IV with 
eupathidia at 0.43V, 0.48V, and 0.67/?, none 
near end of tarsus. Solenidia of tarsi difficult 
to interpret because of convergence in form, 
especially between types s x , s 2 , and s 4 . No 
solenidia referable to type s 3 found on the 
tarsi. Tarsus II with a somewhat heavier 
solenidion, presumably s 2 , at 0.47V, plus about 
12 others presumably Si or s 4 or both. Claws 
of all tarsi simple, smooth, scythe-shaped. 
female: Body 1,378 to 2,574 \x long, 806 
to 1,872 ji wide, length/width = 1.38 to 1.71; 
average of six specimens 1,846 /i long, 1,235 
/x wide, length/width = 1.50. Resembling 
the male in virtually all respects, even the 
genital sclerites and paragenital sclerites being 
only slightly larger and with possibly a very 
few more setae than in the male. Genital 
acetabula distinct, the anterior pair the largest. 
Anal sclerites also as in male. 
LARVA: Body (Fig. 208) 522 to 57 6 /x long 
in partially engorged specimens. Scutum (Fig. 
214) with anterior sensilla short, stiff and 
faintly pectinate; posterior sensilla very long, 
slender, smooth, uniformly tapered. Setae at 
anterolateral and posterolateral angles of scu- 
tum stiff, faintly roughened. Ocular plates 
with two distinct corneae. Cuticle of ocular 
plates and of scutum faintly punctate. Crista 
metopica completely absent. With 48 to 53 
dorsal and marginal setae each borne on in- 
dividual sclerites in the two specimens ex- 
amined; lateral setae more slender than the 
others. Cuticle of dorsum without striae. 
Coxae I and II with two setae each, III 
with three (occasionally four) simple smooth 
setae; intercoxal area completely devoid of 
setae. Coxae I and II close together, urpore 
well developed; a structure of unknown na- 
ture (the " Lassenia organ,” Fig. 209) laterally 
between II and III. Under oil immersion this 
appears to be a plate of much the same form as 
the setigerous sclerites, with the cuticle faintly 
punctate, and with an alveoluslike structure 
on the inner half of the plate. Near the center 
of this alveoluslike structure is a minute pore 
about 0.9 /x in diameter, which opens into a 
delicate chitinous duct about 22 /i long. At 
its inner end this duct expands to form a 
delicate cup or sphere approximately 3.6 /x in 
diameter. The duct is not hydrolyzed by the 
enzymes used to clear the mites. 
Supracoxal setae present in the membranous 
dorsal portion of coxa I, but absent on II and 
III. Postcoxal area with 23 to 27 setae ex- 
clusive of those borne on the anal sclerites, 
all of these setae arising from individual 
feebly developed sclerites with faintly punc- 
tate cuticle (Fig. 221). Anal sclerites mod- 
erately developed, with two to three pairs of 
setae. 
Base of gnathosoma (Fig. 229) devoid of 
setae, cuticle densely and minutely punctate, 
posterior half partly divided by vertical chi- 
tinous septum. Protorostral and tritorostral 
setae long and slender, deutorostral setae 
short and spikelike, posterorosttal setae ab- 
sent. Supracoxal setae rather long and uni- 
formly tapered. Velum very delicate, semi- 
circular in form, consisting of a fimbria of 
extremely delicate chitinous processes extend- 
ing inward toward the mid-line at the tip of 
the rostrum. Chelicerae (Fig. 211) with digitus 
mobilis a soft membranous process, tarsus 
with distal portion slender, scythe-shaped, of 
fairly uniform thickness throughout most of 
length, and typically with two small teeth 
near the end of the tarsus. Trochanter of palp 
(Figs. 210, 213) very short, ringlike, lacking 
setae. Femur greatly swollen and bearing five 
smooth setae on dorsal and posterior aspects. 
Patella incompletely separated from femur 
posteriorly (Fig. 210); with a single dorsal 
