Paleocampa, Meek and Worthen. 291 
accordance of grand features compels us to look upon Palco- 
campa as the precursor of the Chilopoda, we must separate it 
from them in the same way as we separate the Archipoly- 
poda from the Diplopoda. For such a group the name of 
Protosyngnatha is proposed, indicating its ancestral rela- 
tions to the chilopods, or Syngnatha, as they were called by 
Latreille. 
There are, however, two aberrant groups of living animals 
more or less closely related to myriopods, and placed with 
them by some authors, with which also we shall compare 
Paleocampa. The first of these is Peripatus, our knowledge 
of which has been so much increased of late years, and espe- 
cially by the researches of Moseley. 
In external appearance Peripatus resembles an annelid, 
but is furnished with a pair of long jointed antenne, and with 
numerous fleshy tapering legs, each armed at tip by a pair of 
claws; the legs, set wide apart, are obscurely jointed, the 
joints being perceptible only at the extreme tip and on the 
apical half of the mner side, above which are the large elon- 
gated openings into the nephridia. ‘The entire body is of a 
leathery texture with no external sign of segments, or of the 
separation of the head from the rest of the body, except the 
appendages—namely the legs, the nephridia opening on the 
legs, and the ordinary appendages of the head. The same is 
true when the internal structure of the body is examined; for 
neither in the disposition of the muscles nor of the tracheal 
apparatus does it appear that one could judge whether a pair 
of legs represented one or more segments of the body; even 
in the nervous system it is only indicated by a small ganglio- 
nic swelling next each pair of legs. The trachez are like 
extended cutaneous glands, independent of one another, and 
scattered over the body ; and the longitudinal muscles show no 
regular segmental breaks. ‘This weakness of segmental divi- 
sions is nowhere paralleled among hexapods, arachnids, or 
myriopods, and is an indication of very low organization 
among arthropods generally. ‘The number of legs indicates 
from fifteen to thirty-five segments in the body, according to 
the species. ‘The first pair, as they are developed in the 
adult, are functionless as legs, and are situated (in the speci- 
mens I have examined—a South-American species, probably 
P. Edwardsit) midway between the antenne and second pair 
of legs, and not only outside of, but at some distance from the 
mouth-parts, so that the latter are not furnished with auxiliary 
appendages borrowed from a segment behind the first, as in 
chilopods ; this is further proven by the development of these 
parts in the two groups. The body is profusely covered 
above with corrugated papille, without regular distribution. 
