MYRIAPODA 6 1 



his description and figure were based upon it. Karsch gives a meas- 

 urement of 30 mm. and Attems 34-36 mm. by 5.5 mm. ; but the U. 

 S. National Museum has California specimens 38 mm. by 6 mm., col- 

 lected by Ehrhorn at Mountain View. 



Family POLYDESMID^E. 



It was formerly customary to refer to this family all the members of 

 the order Merocheta, but as now limited it consists largely of temper- 

 ate forms of rather small size, the more intimate relatives of the cir- 

 cumpolar genus Polydesmus. 



ANALYTICAL KEY TO THE NORTHWEST AMERICAN GENERA OF 



POLYDESMID^E. 



Body composed of nineteen segments ; dorsum convex, rough with 

 several transverse rows of conic granules Genus Scytonotus. 



Body with twenty segments ; dorsum nearly flat, ornamented with 

 three rows of convex areas Genus Polydesmus. 



Genus Scytonotus C. L. Koch. 

 Scytonotus C. L. KOCH, System der Myriapoden, p. 130, 1847. 



Young and female specimens of a Scytonotus were collected by the 

 Harriman Expedition at Yakutat Bay, Sitka, and Juneau, but without 

 adult males their relationship to the eastern Scytonotus granulatus 

 can not be determined. The figures of Scytonotus shown in plate HI 

 were made from a specimen from the Northwest, in the belief that it 

 was a new species. Subsequently the vial was misplaced, so that the 

 preparation of a comparative description must be deferred. 



Genus Polydesmus Latreille. 



Polydesmus LATREILLE, Hist. Nat. des Crust, et d. Ins., HI, p. 44, 1802, and 

 vii, p. 77, 1804. 



It is to be expected that Polydesmus will be found in Alaska, but 

 in the forest region of the southern part, rather than upon the coasts 

 and islands visited by the Harriman Expedition. 



POLYDESMUS CERASINUS Wood. 



Polydesmus cerasinus WOOD, Proc. Phila. Acad. Sci., 1864, p. 6; Trans. 

 Amer. Phil. Soc., xiil, p. 217, 1865. 



This species was described from Oregon, and specimens apparently 

 referable to it are included in the collection sent by Prof. C. V. Piper, 

 from the State of Washington. 



