288 Mr. S. H. Scudder on the Affinities of 
creature as this could fall excepting worms, myriopods, or the 
larvee of hexapod insects. ‘The certainty that this animal 
possessed a single pair of well-developed legs of identical 
character on every segment of the body behind the first seg- 
ment or head is of itself sufficient evidence to exclude it both 
from the worms and from the larve of hexapod insects. No 
such legs or leg-like structures occur today in worms; and it 
would be idle to look for them in their ancestors of Carboni- 
ferous times. ‘The only approach to such an appearance in 
hexapod larve is in the young of tenthredinous Hymeno- 
ptera, where, however, a difference of great morphological 
significance is found between the true or thoracic legs and the 
prolegs or those attached to the abdomen—a difference based 
on one of the most essential underlying features of their struc- 
ture as hexapods. No such difference occurs in Paleocampa ; 
and it is therefore impossible to conceive of it as the larva of 
a hexapod insect of any sort. 
In myriopods only do we find a repetition of legs of exactly 
similar structure on every or nearly every segment of the 
body *; by this test Paleocampais a myriopod ; and now that 
we have found ancient types of this group, like the Archi- 
polypoda, bearing huge and bristling spines arranged in series 
along the sides of the body, we need not be at all disconcerted 
at discovering this new type with longitudinal series of fasci- 
cles of stiff rods, although we cannot restrain our surprise and 
admiration at their exquisite intricate structure. 
Accepting Paleocampa then as a myriopod, we may next 
ask what relation it bore to the myriopods of the same period 
and found in the same waters, and also to myriopods of to- 
day. The differences between the stout, forked, and bristling 
spines of the Archipolypoda and the close-set but spreading 
bunches of highly organized stiff rods of Paleocampa appear 
upon the barest statement. Were it not, however, for the 
complicated ornamentation of the rods themselves, the dis- 
tinction between the fascicles of Palewocampa and the spines 
of Huphoberia would be hardly greater than that between the 
latter and the long hairs of an undescribed genus of Archi- 
polypoda which has recently fallen under notice; so that to 
this feature alone we cannot grant so high an importance 
as to another which has already been named—the presence 
in Palewocampa of a single pair of legs (and consequently, to 
judge by analogy, of a single ventral plate) to each seement ; 
while there are two ventral plates and pairs of legs to each 
* Some smaller groups formerly, and by some authors still, considered 
as belonging to the myriopods must be excepted from this statement ; 
their relation to Paleocampa will be discussed further on. 
