LITTLE EIVER GEOUP, No. III. 107 



late legs. They appear to have been far more abiuulant in the new world than in the old, 

 and in the latter are scarcely known ontside of Great Britain. 



The ironstone nodules of the shales on Mazon Creek, III., have produced the greatest 

 number and the most remarkable forms of these archaic Mj'riapods, though some have been 

 found in the British carboniferous deposits. Those found at Coldbrook Dale were at first 

 taken to be the caterpillars of certain butterflies, and afterwards as belonging to the Mero- 

 stomata. Myriapods of this family have lately been found at St. John, InT. B. 



A third family of ancient Myriapods is that designated as Archiulidœ by Dr. Scudder. 

 In this group a near approach to Diplopoda of modern Myriapods is seen. The two pieces 

 of the dorsal plate are closely consolidated, but still are distiuctl}' visible, though the anterior 

 is rarely elevated much above the posterior, the body is almost smooth or covered more or 

 less abundantly with serially disposed papillse, ti'om which in some cases hairs or small 

 spines arise. The members of this family resemble modern Diplopoda in their general 

 appearance, much more closely than either of the preceding families. Sir Wm. Dawson, 

 who first discovered their forms in the Palaeozoic rocks, classed them with the Diplopoda, 

 and spoke of them as the oldest "gallj' worms" known. Sii- William's figures would 

 indicate that the back (not the front part as Scudder says) was the more elevated. "While 

 first found in the erect stumps of Sigillarian trees at the Joggins, they have since been 

 detected in the Coal-measures of Great Britain and on the continent of Europe. Possibly 

 also some species found in the Dyas of Bohemia may belong to this family. Two species 

 have been found at Mazon Creek. 



As regards the development of the Myriapods, Dr. Scudder says that in the early life of 

 Pauropus and the Diplopoda, we have what may be fairly considered a true larval form, in 

 which for a brief period after leaving the egg, the body, much shorter than in after life, is 

 provided with three pairs of legs, borne on the anterior segments of the body. These seg- 

 ments are never fully provided with legs, though most of the segments posterior to them, 

 both those which exist during the larval state and those which originate subsequently, bear 

 each two pairs. In tlie Chilopoda on the other hand, although the appendages of the anter- 

 ior segments develop earlier than those behind them there is no true larval condition, or 

 perhaps one may say a larval condition is permanent, in that the same anterior legs become 

 early and permanently developed, as organs subsidiary to manducation, while each segment 

 of the hinder part of the body develops only a single pair of legs. 



To close these remarks it may be said that nine genera of Palaeozoic Myriapods have 

 been recognized in the Coal-measures, and two in the Devonian rocks of Scotland. While 

 of those found at St. John and wliich may to be older, the genera are the same as those of 

 the Coal-measures or are nearl}^ related to them. 



The air-breathing articulates of the plant Vied of St. John so far recognized, consist of : — 



Insects, nine species of eight genera 9 



Myriapods, six species of several genera 6 



Arachnid similar to Anthracomartus 1 



Probable Pedipalp (Eurypterella) 1 



Probable Arachnid or Isopod (Amphipeltis) 1 



Scorpion (Palœophonus arctus) ... 1 



Two species of land snails also have been found, raising tlie number of air-lireathing 

 animals found in the plant beds at S t. John to twenty-one kinds. 



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