THE MYEIAPODA OF NORTH .AMERICA. 159 



Family IV. — Oallipodid^. 

 Includes the genus Callipus of Eisso. 



Suborder II.— POLYDESMOIDEA. 



Contains the following families : 



a. Pleural and ventral plates, except those of the two anterior segments, not free; 

 segments 19 or 20; pairs of legs ( $ ) 28 or ( $ ) 29, or ( $ ) 30 or ( 9 ) 31. 



POLYDES.MI D.E.— V. 



an. Pleural and ventral plates free ; segments 21; pairs of legs 32; shape of body 

 as in the Glomeridce Glomeridesmid.e.*" — VI. 



Family V.— POLYDESMID.F. 



This family is divisible into two subfamilies: 

 a. Body elongate, contractile into a spire; lateral carinae never strongly depressed 



POLYDESMIN.E. — XV. 



aa. Body short, very convex, contractile into a ball; carina? strongly depressed. 



Sph.ehiodesmin.e. — XVI. 



Subfamily XV. — Polydesmin^e. 



Analysis of the genera. 



a. Repugnatorial pores placed on the 5, 7, 9, 10, 12, 13, 15-19 segments. 

 b. Femora of legs not spined. 

 c. A swelling around the repugnatorial pore. 

 d. Anal segment more or less sharp. 

 e. Dorsal plates with a longitudinal sulcus, smooth; lateral carina? small; 



body narrow. 

 /. Body strongly julid; lateral carina; rudimentary or line-like; anal seg- 

 ment decurved. . Strong YLOSOMA Brandt. 

 ff. Body less julid; lateral carina; very plain; anal segment with the end 



excised ORTHOMORPHAt Bollman. 



ee. Dorsal plates not distinctly sulfate; smooth or scaly; lateral carina; 



large; body wide. 

 g. Back convex. 



h. Dorsal plates smooth; lateral carina; not serrate. 



EiEPTODESMUSJ Saussure. 

 hh. Dorsal plates rough; lateral carinas very large and the margins 

 serrate. 



Odontotropis Humb. and Sauss. 

 gg. Back flat. 



i. Repugnatorial pores placed on the upper part of lateral carinae. 



Rhacis Saussure. 

 ii. Repugnatorial pore placed on the lateral margin of carina-. 

 A". Repugnatorial pore surrounded by a round swelling. 



I. Segments with a few indistinct tubercles along the margins 

 (species white) Ch.etaspis Bollman. 



* If Gervais's statements and figures of Glomeridesmus porcellus are true it should 

 represent the type of a new family. It combines a few characters of the Polydes- 

 midat and Glomeridce, under the latter of which Gervais placed it. 



t Ovthomorpha Bollman for Paradesmun Saussure, which is preoccupied. 



} As OxyUriii Koch is preoccupied^ LepfodtiimUd Saussure must bo used instead. 



