Gallery 
VIII. 
Table-case 
20 . 
Wall-case 
12c. 
Table-case 
20 . 
W all-case 
12b. 
104 GUIDE TO THE FOSSIL INVERTEBRATE ANIMALS. 
jaw-limbs, the mandibles and the maxillae, the latter joining 
to form a lower lip. ° 
Millipedes of modern character are found in Tertiary 
rocks, especially in 
amber, e.g. Julus and 
Polyxenus. The Me- 
sozoic rocks furnish 
a single doubtful 
form, Jidopsis, of 
Cretaceous age, and 
a few from the Trias. 
The Palaeozoic forms 
above referred to 
occur in the Devo- 
nian and Carboni- 
ferous rocks. In the 
British series are ex- 
hibited Evx>hohcria 
(Fig. 51) and Xylohius from the Coal IMeasures. 
Fig. 51. — A fo-ssil Millipede, Euphoheria ferox, 
Coal Measures, Coalbrookdale, Shropshire. 
Natural size. 
Class CHILOPODA (Centipedes). 
Superficially like the millipedes, the centipedes differ in 
nevxT bearing more than one pair of legs on a body-segment, 
and in having four pairs of jaw-limbs. The stigmata lie in 
the membrane between the horny rings of the segments. 
These also being dwellers on land, are not common as 
fossils, and up to the present are not represented in the 
Museum. 
Class INSECTA. 
The insects are the most highly modified of Arthropoda. 
Like the centipedes they breathe by tracheae and have a long 
segmented body ; but in addition to a distinct head, the 
hinder part of the body is sharply divided into a thorax of 
three segments in front and an abdomen of nine or ten 
segments behind, and it is only the thorax that retains legs, 
these being always in three pairs. The head bears a pair 
of compound eyes, a pair of antennae, and three jiairs of 
jaw-limbs. Most insects have on the thorax two pairs of 
wings. 
Owing to certain difficulties attending the study of fossil 
