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PACIFIC SCIENCE, Vol. XI, October, 1957 
species of Lassenia known in the larval stage, 
the eupathidial formula is (2-2-1), and the 
dorsal eupathid of both tarsi I and II in both 
species has a basal companion seta. Only in 
Lassenia is there a eupathid on tarsus III, and 
this is subterminal in position. 
The Eupathidia of the Legs of the Adult 
Here we find differences in the distribution 
of the eupathidia on the various segments of 
the legs, with Centrotromhidium having the 
eupathidia confined to the tarsi, and tarsus 
IV typically with only one eupathid. In the 
other three genera, eupathidia are found on all 
segments beyond the basifemur. In all genera 
but Lassenia there is a subterminal eupathid 
on tarsus IV. In Centrotromhidium this lies at 
about 0.85^ to av, in Diplothromhium at 0.90 
to 0.95^ and in Johnstoniana at 0.91 pv. Specific 
differences are found in the distribution of the 
eupathidia on the individual segments of the 
legs. One interesting example is found in the 
genus Lassenia in which ventral eupathidia 
are found on the telofemur, patella and tibia 
of leg I, whereas in L. lasseni all of the eupa- 
thidia are dorsal or marginal in position. 
The Companion Setae 
Companion setae are found only in the 
larvae of some genera, and are seemingly 
universally absent in the postlarval stages of 
all of the Parasitengona. Neither Centrotrom- 
hidium nor Diplothromhium has any companion 
setae in either larval or postlarval stages. 
Johnstoniana larvae have one companion seta 
associated with the dorsal eupathid of tarsus 
I, while in Lassenia there are four companion 
setae. These are associated with s 4 of tibia I, 
Si of tarsus I, and the dorsal eupathid of both 
tarsi I and II. 
The Famulus 
The famulus is the most constant of all the 
specialized setae in the Johnstonianidae. A 
famulus is present on both tarsi I and II in 
all genera, in both larval and adult stages. 
Variations in the position of the famulus often 
provide very useful specific characters (as in 
Centrotromhidium , for example), although a 
noticeable degree of variation in the position 
of the famulus is observed in some species. 
In others the famulus appears to show ex- 
tremely little variation in position. 
The Supracoxal Setae 
The situation here is not certain, although 
it is probable that these are not as variable 
in their number and distribution as are the 
setae on the ventral surface of the coxa. Supra- 
coxal setae, when present, are found both on 
the dorsal surface of the coxal portion of the 
gnathosoma, and on the dorsal surface of the 
coxae of leg I. This appears to be a general 
rule in the Parasitengona. In the Johnston- 
ianidae, supracoxal setae are absent in all but 
the genus Lassenia. In the known species of 
this genus supracoxal setae are present on the 
dorsal surface of the gnathosoma as well as 
on the dorsal surface of coxa I. The distribu- 
tion of supracoxal setae in the adult is always 
the same as in the larva so far as is known. 
The Vestigial Setae 
These are the small spikelike setae at the 
distidorsal end of the patella or tibia of legs 
I and II (Figs. 91, 194, 215). The distribution 
of these very often follows that of the supra- 
coxal setae, that is, when the latter are present 
vestigial setae are also present. This is true in 
both Centrotromhidium and Diplothromhium in 
which none of the described species has 
either supracoxal or vestigial setae. In Lassenia 
lasseni and L. spinifera , vestigial setae are found 
on patella I and II and on tibia I; likewise 
supracoxal setae are present on the palpi and 
leg I. In Johnstoniana latiscuta an intermediate 
condition is found; for although there are no 
supracoxal setae, vestigial setae are present on 
patella I and II but are absent from all tibiae. 
As in the case of the supracoxal setae the 
distribution of the vestigial setae is identical 
in larva and adult in all species studied. The 
distribution of the supracoxal and vestigial 
