286 S. H. SCUDDER ON NEW TYPES 



the rods themselves, the distinction between the fascicles of Palaeocampa and the spines of 

 Euphoberia would be hardly greater than that between the latter and the long hairs of 

 Trichiulus; so that to this feature alone we cannot grant so high an importance as to an- 

 other which has already been named : the presence in Palaeocampa of a single pair of legs 

 (and consequently, to judge by analogy, of a single ventral plate) to each segment; while 

 there are two ventral plates and pairs of legs to each segment in Archipolypoda. This is 

 a difference of profound significance, which has separated the prevailing types ofmyriapods 

 down to the present day, lying as it does at the base of the distinctions between the living 

 chilopods and diplopods. The discovery of this type is of the greater importance because 

 we have hitherto known nothing of any chilopodiform myriapods previous to tertiary times, 

 unless Minister's dubious Geophilus proavus from the Jura possibly be an exception. 1 



In studying the Archipolypoda we necessarily confined our comparisons with modern 

 types to the Diplopoda, because of their common possession of the fundamental feature 

 just named ; in the same way the comparisons between Palaeocampa and recent forms 

 must be reduced to the common features or the radical distinctions which appear in study- 

 ing the Chilopoda. Now although the structure of Palaeocampa can be far less perfectly 

 known than that of the equally ancient Euphoberia and its allies, enough can be seen to 

 point conclusively to wide and important differences between it and modern Chilopoda. 



In Chilopoda, of which the modern scolopendra or centipede is the type, the body is al- 

 ways depressed, formed of many segments, rarely as few as sixteen behind the head, each 

 of which is compound, being formed of two sub-segments, one of them atrophied and carry- 

 ing no appendages; both dorsal and ventral plates are coriaceous, of nearly equal width, 

 and possess no armature whatever excepting the simplest huirs, which are occasionally scat- 

 tered over the surface. The larger sub-segment bears a single pair of legs, which are com- 

 posed of five slender, cylindrical, sub-equal joints beyond the coxa, and armed with a single 

 apical claw ; they are attached to the interscutal membrane uniting the distinct dorsal and 

 ventral plates of each segment and are therefore separated by the entire width of the broad 

 ventral plates. The hindmost legs are transformed to anal stylets, while the first two pair 

 are more profoundly transformed to subsidiary mouth parts, the first becoming palpi and 

 the second stout nippers. The head really composed of eight primitive segments, is appar- 

 ently made up of two, each of which is generally of about the same size as the body seg- 

 ments and as distinctly separated ; the stout biting jaws, composed of the second pair of 

 legs, spring from this second segment of the head, and the palpi or first pair of legs from 

 the hinder part of the first cephalic segment; the anterior part of the same bears the 

 many-jointed simple antennae. 



Passing now to the comparative study of Palaeocampa, we find that its body was in all 

 probability cylindrical, composed of a limited number of segments behind the head, and 

 the head itself, considerably smaller than the body segments, is composed of only a single 

 apparent segment. The legs of the segment immediately succeeding it are in every respect 

 like those of the rest of the body, and have nothing whatever to do as auxiliary to the mouth. 

 In this point alone we have a distinction as wide and incisive as any which separate the 

 modern Diplopoda and Chilopoda. In the body segments we discover no trace of anything 

 more than a simple ring without sub-division, but as the specimens indicate a coriaceous 



1 Hagen considers this a nereid worm, a suggestion I once adopted, but now find reason to question. 



