THE CRYTOPS S AVION I. 
425 
undergo changes somewhat like the Julidce before attaining the 
adult stage. The species of the genus Crytops, when full grown, 
have inconspicuous eyes, seventeen joints to the antennae, and 
twenty-one pairs of feet. But when they are young they have no 
mouth, and nothing like it is to be seen when the microscope is 
used ; there is, however, a rounded aperture at the back of the 
head, and fringed at its margin. It is remarkable that one of 
the species of the genus, Crytops Savigni, should have no less than 
twenty-nine joints to its antennae in its imperfect state, but 
only seventeen in the adult form, so that there is a retrograde 
development during the successive moultings and the corres- 
ponding structural changes. 
One genus, Scutigera , has a slim body, but very great legs 
and antennae ; and the growth of Scutigera araneoides is very 
remarkable, according to Fabre, especially with reference to the 
front and hind parts of the body. The young are furnished with 
only seven pairs of feet ; but during development the number of 
the segments, legs, and ocelli, besides the number of the joints of 
the antennae and tarsi, increases. The segments which bear the 
first seven pairs of feet, and which exist at the moment of birth, 
form the half of the body which contains the organs of the senses 
and the essential parts of the digestive apparatus; whilst the 
other half, which lodges the reproductive apparatus, is developed 
subsequently. Fabre appears to consider that the first part 
represents the larva, which only manifests the life of the individual, 
and the posterior portion the perfect insect, in which resides the 
life of the species. This fancy may be of course applied to the 
case of the Julus; but it only testifies to the vivid imagination 
of an able naturalist. The same author has observed the phases 
in the development of Lithobius forficatus. It is born with ten 
segments, seven pairs of feet, seven joints on its antennae, and 
two ocelli. Two months elapse, and the Myriapod is observed to 
have seventeen segments, fifteen pairs of feet, six ocelli on each 
side of the head, and twenty-six joints to its antennae. 
The Myriapoda are very ancient creatures, and doubtless the 
Julus that was found in a tree stump in a coal seam in Nova 
Scotia by Dr. Dawson took as long to mature during a series of 
moults, which imitated metamorphosis, as its modern descendants. 
