430 Dr. H. J. Hansen on the Morphology of the 
latter throughout almost the whole of its length is connected 
with the lateral wall of the head. Consequently the man- 
dibles and maxillz do not really lie within the head at all, 
but, as in the case of Machilis, are attached to the integument 
of its sides, which has here become thin and smooth; and 
since the articular region of the inner lobes of the maxille 
and labium has undergone elongation, we understand how the 
reduplicature can extend almost as far as the end of the 
labium. (The necessary investigation is difficult, since the 
integument on the inner side of the reduplicature and on the 
portion of the lateral wall of the head which is covered by 
the reduplicature is very thin.) 
37. The musculature of the mandibles resembles that of 
the Crustacea even more than it resembles the musculature of 
Machilis. It is only necessary to compare Meinert’s figure of 
Japyx with my figure of Diastylis Goodsiri in ‘ Dijmphna- 
Togtet ” (I have only reproduced the three largest muscles or 
their tendons), or with Sars’s figure of Diastylis sculpta, to be 
struck by the astonishing agreement in the form and direction 
of the muscles and of the large median muscle-plate. The 
mandibles are without a pars molaris, but, on the other hand, 
we find in Campodea @ small lacinia mobilis. 
38. The maxille consist of a cardo and second segment, 
which (as in Machilis) is continued into a lobe exhibiting a 
transverse segmentation in the neighbourhood of the tip. On 
the other hand, the third segment and the palpus are entirely 
wanting. What is termed by authors the outer lobe and 
palpus is not connected with the maxille (see especially 
Stummer-Traunfels, ‘‘ Vergleichende Untersuchungen iiber 
die Mundwerkzeuge der Thysanuren und Coilembolen,” 
Sitzunesber. k. Akad. Wiss., math.-naturw. Cl., c. Bd., iv. 
Heft, Wien, 1891, Taf. i. figs. 7, 10, 11) and does not 
belong to them, but is, on the contrary, united to the 
‘ paraglosse ” and to the underside of the skeleton of the head 
which is covered by the labium. 
39. In Japyx solifugus the hypopharynx is short and 
rounded off; the firm chitin of the ‘ paraglosse ” is articu- 
lated to the chitin of the head behind the base of the hypo- 
pharynx. The paraglosse themselves lie in front of the latter 
and coalesce with it for a certain distance; each of these 
‘secondary tongues ” is on the outer side connected by means 
of firm chitin with the outer lobe alluded to in § 38, and with 
a distinct three-jointed palpus. This entire structure, which 
lies in front of the maxilla, constitutes the conspicuous and, 
in their basal portions, somewhat abnormally constructed 
maxillule. The inner lobe is the “ paraglosse ” ; the other 
two portions become the outer lobe and palpus. In the 
