S. II. Scudder— Diversity of Typ '>» <",<■;, „t Myriapods. 169 



rods in the fascicles of Palaeocampa paralleled by the well- 

 known delicacy of organization of the scales in other Thvsan- 

 ura, though they do not exist in Scolopendrella. The limited 

 number of abdominal segments might be looked upon as a 

 further point were it not that the number is even less than in 

 Scolopendrella or in the Cinura; and that the Pauropida 

 among diplopod myriapods have in some instances even a still 

 smaller number. <3n the other hand, the character of the legs, 

 tii- apparent absence of a double claw at their tip, the pecul- 

 iar armature of the fascicled rods, which forms so striking a 

 feature in Paheooampa. the warn of any caudal stylets, and the 

 complete uniformity of the segments of the body unprovided 

 with distinct dorsal scutes, distinguish Pakeocampa not only 

 from Scolopendrella but from all Thysanura whatever: the 

 general form of the body, too, is I from any- 



thing occurring there, even its cylindricity being foreign to the 

 Thysanura, excepting in their highest types among the Col- 

 lembola. It seems therefore clear that the points of affinity 

 between Palaeocampa and Scolopendrella, with the single 

 exception of the separation of the head and its a] 

 from the body, are precisely those in which Scolopendrella is 

 chilopodan, and that the assemblage of features which our fossil 

 presents are therefore chilopodan rather than thysanuran. 



Regarding Palaeocampa then as a myriapod, though of a 

 type very distinct from any known, whether living or fossil, 

 we are brought face to face with two remarkable and some- 

 what parallel facts: First, that in this ancient myriai>od> as old 

 as any with which we are acquainted, carrying us back indeed 

 as far as any traces of wingless traelieate arthropods have been 

 f«>und, and "therefor, presumably not f.u from the origin of this 

 form of life upon the earth, we find dermal appendages of an 

 extraordinarily > ih < , > > .>' > , j i >re c< ' ; > t i. as we have 

 pointed out. than anything of the sort found in living arthro- 

 pods, excepting the more varied but not more exquisite scales 

 of several orders of hexapods; a form of appendage which it 

 would seem, on any genetic theory of development, must have 

 required a vast time to produce jmt which we now seem to 

 find at the very threshold of the apparition of this type of 

 arthropod life. 



Second, that at tin, nirly p-ri<A, in marked contrast to what 

 we find in other groups of articulated animal-, //<• 1 1. in:, -genres 

 <>f ' ^trwhi.rr among „,yri<tp,«Is a: as as great as it is to-day. This 

 is the more surprising because we possess only imperfect 

 remains of a few types, and yet from what we already know of 

 the Arch ipolypoda on the one hand, and of the Profosyngna- 

 tha on the other, they are found to differ quite as much as the 

 Diplopoda and Chilopoda, and in points fully as important as 



