4 Dr. S. Woodward — Myriapods of the Coal Period. 



of only a single plate ; but the ventral portion (sternum) is seen to be 

 composed of two narrow parallel plates ; and as each somite bears 

 two pairs of legs, and two pairs of spiracles, it seems certain (says 

 Claus) " that they may be regarded as double-segments/ formed by 

 the fusion of two somites." 



The raised anterior portion of the tergum of each segment is pro- 

 vided with a series of spines or tubercles, which, in some of the 

 Mazon Creek specimens, are doubly-forked. 



The class Myriapoda, at the present day, is divided as under, 

 viz. : — 



I. QiBiJiOVODk^Centifedes). Antennae simple, body depressed, dorsal 

 and ventral plates horny, united by a membrane ; the legs 

 inserted in single pairs at the sides of the segments, with the 

 exception of the first two pairs, which are converted into 

 mouth-organs. 

 IT. DiPLOPODA = Chilognatha {Millipedes). Antenna3 simple, 

 body convex, or even cylindrical, the dorsal plates bent round 

 so as to meet the narrow ventral plates nearly in the middle 

 line of the body; each segment after the 5th or 6th with two 

 pairs of legs. 

 III. Patjropoda. With branched antennae. 



If we take the broadest possible lines for our guidance in the 

 classification of animals, it seems that Scudder's PKOTosvjfGNATHA 

 will fall under the first of these divisions, viz. : — 

 Order I. Chilopoda {Centipedes, recent). 

 Suborder Protosyngnatha {Palceocampa, fossil), 

 and his Archipolypoda will in the same manner find a place under 

 Order II. Diplopoda {Millipedes, recent). 



Suborder Archipolypoda (all Palaeozoic forms), with the follow- 

 ing species : — 



1. Family Archidesmid^, Peach. 

 Genus Arehidesmus, Peach. 



1. ,, Macnicoli, Peach, Old Eed Sandstone, Forfarshire. 



2. ,, Forfariensis, Page, Old Eed Sandstone, Forfar. 



2. Family Euphoberid^, Scudder. 

 „ Acantherpestes, Meek and Worthen, 1868. 



3. ,, OTffyor, Meek and Worthen, Coal-measures, Illinois, U.S. 



4. ,, [Brodiei, Scudder, Coal-measures, Coalbrook-dale.^) 

 ,, Euphoberia, Meek and Worthen, 1868. 



5. ,, ferox, Salter, Coal-measures, Staffordshire. 



6. ,, horrida, Scudder, Coal-measures, Illinois, U.S. 



7. ,, armigera, Meek and Worthen, Coal-measures, Illinois, U.S. 

 . 8. ,, Brownii, H. Woodward, Coal-measures, Ayrshire. 



9. ,, granosa, Scudder, Coal-measures, Illinois, U.S. 



10. ,, Carrii, ,, „ ,, 



11. ,, Jlabellata, ,, ,, ,, 



12. ,, anguilla, ,, „ ,, 



1 Not originated from a fusion of two primitively distinct segments, hut from a 

 later imperfect division of each of the primitive segments into two, and the supply 

 to each of the divisions of a primitive segment of a complete set of organs." — 

 (Balfour, Embryology, vol. i. p. 392.) 



2 This is shown to be merely U. ferox, Salter, sp. ; see ante p. 2, and infra p. 6. 



