96 Canadian Record of Science. 



Modern Myriapods are divided into three orders, Chilo- 

 pods, Decapods and Pauropods ; the third of which, only 

 known as Recent, is insignificant both in numbers' and size. 

 Dr. Scudder was once disposed to claim that these orders 

 like those of the True Insects had originated in the Second- 

 ary Rocks (Mesozoic), and that all the Palaeozoic Myriapods 

 were included in his new orders, Palseosygnatha and Archi- 

 polypoda ; but he has since discovered examples of the 

 Chilopod forms in the Carboniferous beds. It follows that 

 three if not four of the orders of the Myriapods existed in 

 the Palaeozoic rocks. 



The (Jhilopods are distinguished from the Diplopods by 

 the possession of only one pair of feet to each joint of the 

 body, whereas the Diplopods have the ventral plate of eaoh 

 joint in two pieces and carry two pairs of legs to each joint 

 except a few anterior joints which have only one pair; 

 their feet therefore are twice as numerous as those of the 

 Chilopods (except on the anterior joints). The Chilopods 

 differ also in having the body flattened. Some small species 

 of this order has been found in the plant beds at St. John. 



Dr. Scudder has made a separate order, Protosygnatha, 

 of that singular larva-like form described by Meek and 

 Worthen under the name Palseocampus. It has only a few 

 joints (12) and is covered with tufted bristles. AMyriapod 

 with the bristles more uniformly diffused and having more 

 numerous joints occurs at St. John. 



Omitting Protosygnatha and the few Chilopods from 

 view, the bulk of the Palaeozoic Myriapods are included in 

 the extensive order Archipolypoda, characterized by a 

 rounded body of many joints, and having the ventral 

 plate of each somite as in Diplopoda divided into two 

 pieces, with a pair of legs attached to each piece. The an- 

 terior half of each dorsal plate is elevated, ridged trans- 

 versely to the body and frequently bears spines or tubercles ; 

 while the posterior portion is flatter and lower. The body 

 in the Myriapods of this order is elongated, fusiform, 

 largest in the middle or towards the anterior end, and is 

 composed of many segments. 



