23 G SYNOPSIS OF NORTH AMERICAN MYRIAPODA. 



S. rubens.-f Pairs of feet 50. 

 S. Whitei.f Pairs of feet 76. 



Ord. II. DIPLOPODA. 



Each fully developed segment of the hody provided with two pairs of feet. 



Sub Ord. STKONGYLIA. 

 Mouth furnished with jaws suitable for the mastication of vegetable matters. 



Fam. polydesmid.e. 



Sternum and scutum of each segment fused together into a complete ring. Body com- 

 posed of few segments ; each furnished with lateral laminae. 



Gen. Polydesmus. 



Lateral pores on the 5 — 7—9—10—12—13—15 — If)— 17— 18 — 19 scuta. 



Subgenus Polydesmus. 



Dorsum complanate. Lateral laminae large, horizontal. 



P. setiger* Scuta with minute, obtuse, tuberculoid scales (sometimes obsolete) with a 

 row of acute, conical, seta-tipped tubercles along the posterior border. 



P. granulatus* Scuta covered with convex, obtuse, tuberculoid scales, arranged in four 

 more or less irregular transverse series ; none of them seta-tipped. 



P. Mspidus.^ Scuta with scales in five series. 



P. serratus. Scuta with 9 — 10 complanate scales, arranged in two series, besides a 

 third obsolete series. 



P. Canadensis. Color brown. Scuta with 8 scales, arranged in two series. 



P. cerasinu8. Color cherry-red. Scuta like in P. Canadensis. 



Subgenus Paradesmus. 



Dorsum moderately convex. Lateral lamina? large, horizontal. 



P. erythropygus. Olive-chestnut ; scuta with a large orange spot on their posterior sur- 

 face. Lateral laminae orange. Anal scutum broad, prolonged. 



P. hispidipes. Olive-brown, immaculate. Anal scutum triangular. 

 Var. "? Ornamented with small orange spots. Lateral laminae orange. 



Subgenus Fontaria. 



Dorsum convex. Lateral laminae large, depressed. 



P. Virginiensis. Chestnut, with yellowish lateral lamina". 



* Probably tbeso two species belong to a new genus. 



