58 Mr. J. Wood-Mason on Scolopendrella. 
anterior or apical, and two are short and posterior or basal ; 
two median ; and one or two basal. The two median sclerites 
are much broader than the long laterals; and they form toge- 
ther a broadly spatulate figure, which extends quite up to the 
toothed and lobed anterior margin of the head in front, and 
behind is divided into two divergent horns embracing the 
sides of the triangular basal sclerite. The long or apical 
lateral sclerites are attached not only to the medians and by the 
basal moiety of their outer margins to the ventral margin of 
the basal joint of the mandibles, but also by the intermedia- 
tion of the short laterals to the basal part of the basal sclerite, 
which may be divided transversely into two parts; and they 
taper from their base to their apex, which reaches only to 
the end of the first mandibular joint and carries two large 
movably articulate appendages. These ordinarily le with 
their apices all directed towards one another in the middle line, 
concealed beneath the rounded end of the conjomed median 
lobes ; but when pressure is put upon the covering-glass they 
diverge and project straight forward for some distance beyond 
the front of the head *. They both lie in the same plane; and 
the outer (which is a highly indurated, slender, straight, and 
tapering organ, hooked at the extremity and provided inter- 
nally with a minute anteapical spiniform process) fits the 
inner (which is a soft finger-shaped body with a brush of 
apparently implanted bristles on its inner extremity) as the 
““oalea” does the “lacinia” in the first maxilla of the 
cockroach—with which parts of the insectean maxille they 
can have nothing whatever to do, being plainly homologous 
with the two short and similarly convergent appendages that 
are present at the end of each outer lobe of the same pair of 
jaws in all Chilognatha, and being probably, like these and 
like the tips of the mandibles, modified pairs of claws inherited 
from the common Protracheate ancestor. 
Third Pair of Postoral Appendages.—Of the fifteen dorsal 
sclerites which in adults follow the head, the first is little 
more than a mere short and transverse fold of skin with 
scarcely a trace of the conspicuous imbricating process given 
off from the posterior margin of all its successors ; it is the 
tergum of the somite that bears the first pair of legs. These 
differ from those of the remaiming eleven pairs in being 
conspicuously smaller and slenderer, with their last joint 
elongated, and their last but one shortened and apparently 
confounded with the third, in bemg more approximated at 
* The fore margin of the median lobe also becomes protruded so as to 
display the six conical spines with which it is furnished. 
— 2.0 
