morpha; and
it shows how the Lithobiomorpha may be derived from a
Scolopendromorphous type most nearly resembling _Plutonium_ by the
excalation of the third, sixth, ninth, eleventh, fourteenth and
seventeenth leg-bearing somites.

_Order 4. Lithobiomorpha._ Chilopoda with fifteen pairs of leg-bearing
somites differentiated into larger and smaller, the 1st, 3rd, 5th,
7th, 8th, 10th, 12th and 14th being large, the others small. Spiracles
present upon all the larger with the exception sometimes of the 1st.
The toxicognaths are relatively weaker than in the orders hitherto
considered, and have their basal segments less firmly fused mesially.
In correlation with their weaker muscularity the first leg-bearing
segment is relatively small. The gonopods, present and usually jointed
in both sexes, are especially well developed and forcipate in the
female, and arise from a large ventral plate resulting from the fusion
of their coxae with the sternum of the genital somite. The antennae
are many-jointed, and there is a single ocellus or a cluster of ocelli
on each side of the head. The coxae of the legs are large, and those
of the last four or five pairs usually contain glands opening by large
orifices. The newly-hatched young has only seven pairs of legs, the
remaining pairs being successively added as growth proceeds.

The genera of this order are divisible into three families, the
_Lithobiidae_ (_Lithobius, Bothropolys_), _Henicopidae_ (_Henicops,
Haasiella_), the _Cermatobiidae_ (_Cermatobius_). _Cermatobius_, based
upon a single species, _martensii_, from the isl. of Adenara, is of
peculiar interest, since in the absence of coxal pores, and the length
and multi-articulation of the antennae and tarsal segments, it
approaches more nearly to _Scutigera_ than does any other
pleurostigmous Chilopod. It is also stated that the spiracles have
assumed a more dorsal position, thus foreshadowing the completely
dorsal situation they have taken up in the Notostigma. The
_Henicopidae_, containing centipedes of small size, attains its
maximum of development in the southern continents and islands, more
particularly Australia, New Zealand, South Africa and South America.
One genus (_Lamyctes_) however, occurs in Europe. The _Lithobiidae_,
on the contrary, are almost exclusively northern in range, being
particularly abundant and of large size individually in Europe,
ext