THE MYRIAPODA OF NORTH AMERICA. 187 



of the antenn<e. Anal segment . Anal valves small, smooth; 



anal scale absent. Lateral carinas . Repugnatorial pore be- 

 ginning at the fifth segment. 



Polyzonium rosalbum. 



Petaserpes rosalbus Cope. Trans. Aiuer. Ent. Soc, 65,1870 ( Cumberland Mountains, 



Tenn.). 

 Bexaglena cryptocephala McNeill. Proc. U. S. Nat. Mus., 328, 1887 (Bloomington, Ind.). 



OCTOGLBNA. 



1864. — Octoglena Wood. Proc. Phila. Acad. Nat. Sci., 186 (bivirgata). 



If we can trust the figures of Wood showing the head and a few seg- 

 ments of Octoglena bivirgata, this genus differs from Polyzonium by hav- 

 ing the first segments marginate and not concealing the ocelb'. 



If his figures are not trustworthy Octoglena is equal to Polyzonium. 



This genus contains the following species: 



Octoglena bivirgata. 



Octoglena bivirgata Wood. Proc. Phila. Acad. Nat. Sci., 186, 1864 (Georgia) ; Wood, 

 Trans. Ainer. Phil. Soc, 229, 1865. 



B. — Pjlatydesmin^. 



I860. — Platydesmii Saussure. Myr. Mex., 83. 



1872. — Platydesmia Humbert and Saussure. Miss. sci. Mex., vi, 99. 

 1884. — DoUstenia Latzel. Myr. Ost.-Ungar. Monarch., n, 362. 

 1887. — Platydesmini Pocock. Ann. and Mag. Nat. Hist., 225. 



Analysis of the genera of Platydesminai. 



a. Body narrow, filiform ; mentum rectangular ; hypostoma not well developed; anal 

 scale absent ; segments not tuberculate. 



b. Fifth segment normal, pores not carried on a pedicel Dolistenus. 



bb. Lateral carinas of fifth segment large, deeply sinuate, anterior lobe directed 

 forwards and bearing the repugnatorial pore, which is raised on a short 

 pedicel ; other pores on a pedicel but openiug on the posterior half of seg- 

 ments Andrognathus. — III. 



aa. Body wide, depressed; mentum hammer-shaped; hypostoma well developed; 

 anal scale present ; segments tuberculate Platydesmus. — IV. 



ANDROGNATHUS Cope. 



1869. — Andrognathus Cope. Proc. Amer. Phil. Soc, 182 (corticarius) . 



Body narrow, fifiform, convex above and below, covered with numer- 

 ous short hairs. Head not rostrate (mouth parts not adapted for suck- 

 ing), not concealed by first dorsal plate, densely pilose. Antennae 

 clavate, short. Ocelli absent. Gnathochilarium well developed, stipes 

 acuminate, destitute of mola and teeth ; hypostoma rectangular; cardo 

 rather long and narrow, triangular; mentum rectangular; promentum 

 elongate-ovate; lingual plates, acuminate, separate, destitute of lobes. 

 Dorsal plates median! y sulcate, not tuberculate. First dorsal plate 



