420 
proximatum n. sp. was found at the latter 
locality. This is very similar to C. distans but 
differs in at least three consistent respects. 
Because of the high degree of variation found 
in the Johnstonianidae and the terrestrial Pa- 
rasitengona in general, it is often difficult to 
assess the significance of small variations be- 
tween individuals. However, all individuals 
of Centrotrombidium seen by the writer fall into 
one of two groups depending upon the de- 
gree of separation between the clavate soleni- 
dion 2 and the famulus on tarsus II (Figs. 6, 
49). In both males and females of C. distans 
these are widely separated as described above; 
whereas in the others the clavate solenidion 
and famulus are very close together. More- 
over, the famulus in C. distans is borne on a 
protruding vesicular base while that of the 
other form arises from an alveolus which is 
set at or below the general surface of the 
cuticle. The second arrangement has been 
found in both males and females so that 
sexual differences are not involved. A second 
difference is in the number of solenidia on the 
dorsal surface of tibia I. These segments are 
approximately the same size in the two forms, 
but in C. distans there are approximately 34 
to 41 solenidia; whereas in the second form 
there are only about 20. A third difference, in 
the form of the scutum, is discussed in the 
description of C. approximation. 
Centrotrombidium approximatum new species 
female: Very similar to Centrotrombidium 
distans new species in size and general appear- 
ance. Length 988 to 1092 /jl to tip of scutal 
spine, width 728 to 884 jit, length/width 1.23 
to 1.35; average 1050 ji long, 801 /x wide, 
length/width 1.31 (five ovigerous females). 
Scutum slightly larger than in C. distans , with 
the portion behind the area sensilligera of 
nearly uniform width throughout in contrast 
with the expanded form of this part in C. 
distans . Crista metopica well developed, the 
portion between the area sensilligera and the 
scutal spine being somewhat longer generally 
PACIFIC SCIENCE, Vol. XI, October, 1957 
than in C. distans , but this is a variable feature. 
Posterior sensilla spherical distally, anterior 
sensilla absent; scutum with only one pair of 
setae in addition to the sensilla. With 2 to 
8 setae between the scutum and each ocular 
plate (average 4.5 setae, six specimens). Ocu- 
lar plates appreciably larger than in C. distans 
(Fig. 53) bearing a single cornea laterally and 
a large lobe medially. The medial lobe is 
punctate like the rest of the ocular plate, and 
apparently is never tuberculate as it frequently 
is in C. distans. Dorsal and marginal body 
setae apparently slightly longer than in C. 
distans , each borne on a separate sclerite, but 
these sclerites are more nearly hemispherical, 
and noticeably less elevated than in the pre- 
ceding species (Fig. 57). Membranous cuticle 
of dorsum smooth, subcutaneous reticular 
layer as in C. distans. 
Coxae I and II with 27 and 26 smooth, 
slender setae each, pars medialis coxae with 
5 setae (one specimen). Coxal ring I incom- 
plete dorsally, supracoxal setae absent; coxal 
ring II complete. Both I and II with a large 
articulating process in anterior portion of 
coxal ring (Fig. 54). Intercoxal area of I and 
II with 9 to 20 smooth, simple setae, each 
borne on an individual sclerite; no apodemes 
behind II. Coxae III and IV with 27 and 25 
smooth slender setae respectively in specimen 
counted, coxal rings complete dorsally; also 
with a prominent articular process on the 
anterior half of the coxal ring. Genital and 
paragenital sclerites as in C. distans (Fig. 10), 
genital sclerites with a single row of 9 to 11 
setae, paragenital sclerites with a single to 
double row of 12 to 17 setae. Three pairs of 
genital acetabula. Anal sclerites also as in C. 
distans , with 6 to 10 setae on each side. 
Base of gnathosoma essentially as in C. 
distans but with a larger number of setae (6 
to 10). Velum directed anteriorly, protorostral 
setae of same form as in C. distans; a pair of 
ventrally directed setae distiventrally on ros- 
trum as in the case of C. distans. It appears 
probable that these are the tritorostral setae, 
for between these and the protorostrals is a 
