NEW JAPYGIDAE—EWING AND FOX 299 
region of the eighth abdominal segment can be clearly detected the 
chelicerae and some other parts of a mite of the family Parasitidae. 
The single specimen of JV. tropicalis is of further interest because it 
has been prepared in such a way as to exhibit the musculature. Advan- 
tage is taken of this fact to record some observations on the muscles 
of the proximal part of the antenna. These notes supplement the 
descriptions and figure of the same part of the antenna of a species of 
Japyx already given by Imms.’ In general the number and arrange- 
ment of the muscles (pl. 34, fig. 9) are the same as reported by Imms 
for Japyx, but the following should be noted: 
Segments II and III appear to be articulated firmly in the manner 
of a hinge, there being an exceedingly short articulating membrane 
between the two. This condition prevents III being telescoped into IT, 
and restricts the movement between the two segments to a single plane, 
which in this instance is vertical. Imms describes two muscles for 
segment II, a levator and a depressor. In the case of WV. tropicalis it 
is not clear whether there is a single muscle with two heads or two 
distinct muscles as shown by Imms. 
An examination of the structures illustrated in plate 34, figure 9 
indicates rather conclusively that this large muscle in segment IT is 
the same as the large, diagonal levator of III, which in turn must 
be the same as the smaller and less diagonal levator of IV, which is 
undoubtedly the same as the longitudinal levator muscle found in each 
succeeding segment. Thus this same muscle, found in the segments 
beyond the first, retains almost without change its place of insertion 
and its function, while its origin shifts from the anterobasal to the 
posterobasal region of the segment in which it occurs. 
In segment I there is a very interesting muscle, since its origin is 
from almost a single point, while it is spread out like a fan at its 
place of insertion. Concerning it Imms states, “The functions of this 
muscle are not wholly clear.” In Japyx, according to Imms, “some of 
its fibres are inserted onto the base of segment II * * *.” He also 
states that the origin of the muscle is on the border of the scape. In 
MV. tropicalis the insertion of this muscle is entirely on the anterodorsal 
aspect of segment I and its origin from the sclerotized and elevated ring 
of the head capsule to which the base of the antenna is articulated. 
Its function in the case of this species is clear, i. e., it retracts and turns 
inward segment I. 
1 Quart. Journ. Micros. Soc., vol 81, pt. 2, p. 280, 1939. 
