THE MYKIAPODA OF NORTH AMERICA. 141 



18. POLYDESMIX.K. 



1872. Polydesmia Humbert ami Saussure. Miss, scientif. Mex. /ool., vi, 25 (teste 



Latzel). 

 1880. Cryptodesmoidea Karsch, Mittkeil. Miiuch. Ent. Ver., 143. 



The subfamilies of Poly<lexnii<l<v established by Humbert and Saus- 

 iSure and also retained by Latzel seem to me to be worthy of their rank. 



In accordance with common custom I have changed Polydesmia to 

 Potydesmince. 



19. SPH/ERIODESMINJS. 



1872. Sphfvriodesmia Humbert and Saussure. Miss, scientif. Mex. Zool., vi, 20 (teste 

 Latzel). 



20. LEPTODESMUS. 



1847. Oxyurus Koch. Syst. Myr., 60 and 139 (restitua). 



1859. Leptodesmus Saussure. Linu. Ent., xm, 323 (granulosus). 



As Oxyurus Koch is preoccupied (Oxyurus Baf., Pisces, 1810; Oxyurus 

 Swains., Aves, 1827), Leploih-xmus Saussure must be employed instead 

 of Oxyurus. 



21. RHACOPHORUS. 



1847. Rhacophorus Koch. Syst. Myr., 59 and 137 (Poly, conspersus Perty). 



1864. CryptodrxniHs Peters. Mouatsber. kon. preuss. Akad. Wiss., 621 (alatm, etc.). 



Cryptodcsmus has been rightly considered by Latzel as being a sub- 

 genus of Rhacophorus. 

 The following is a key to the subgenera: 



a. First dorsal plate normal, not concealing the head ............... RHACOPHOKUS. 



aa. First dorsal plate strongly produced forward and completely concealing the head. 



CRYPTODESMTS. 

 22. STENONIA. 



1842. Stenonia Gray. Todd's Cyclop. Anat. and Phys., in, 546 (druii). 



IX-n.Platurhacus Koch. Syst. Myr., 59 and 131 (>i<'aber = Stenoni(i, . xtr.). 



1S60. Oddntiidrxiniix Saussure. Myr. Mex., 70 (jaranHx). 



1S64. .ininlliodcxmiix ]'ctt-rs. Monatsber. ktin. preuss. Akad. Wiss., 547 (xcutatus, etc.) 



rintyi-hacus, OdontodcNmus and Acanthodetsmm have been considered 

 as subgenera of MrHonia; but as Stenonia has not been proi)erly sub- 

 divided no sul)g('iius Mrmntiii having been set apart I have comj)iled 

 the following analytical key for the separation of the subgenera: 



. Hasal joint of legs not provided with a spine. 



b. Body slender, lateral carina- moderately developed, repuguatorial pores sub- 



marginal, second dorsal plate iiiurh wider than thr first ..... ODONTODKS.Mrs. 

 bh. Body wide; lateral canna- strongly developed ; repuguatorial jxires superior. 



more or less distant from lateral margin of earina- : second dorsal plate normal. 



STENONIA. 



mi. Basal joint of legs armed with a spine ....................... ACANTHODKSMUS. 



23. SCYTONoifs. 



1847. Scytonotuii Koch. Syst. Myr., .~>7 and 130 (scabricoUi8 = ijrunulatnx Say). 

 [SQi.Trachelodeamus Peters. Mouatsber. kirn, preuss. Akad. Wiss., 623 (const) ictus). 



