357 



Length about 58 mm.; width of 10 th somite 6.5; of 1 st 5.5, length 

 of 1 st 2.3. 



52. Platyrhachus œquidens sp. n. PI. XXI, fig. 3 — 3 b . 



Sumatra: Ajer Mantjur. 



So closely related to the preceding species as to render a detailed 

 description unnecessary. 



Colour; head, antennse fuscous; somites nearly black, the keels 

 being yellowish white, with the black of the dorsal surface spreading 

 on to them at the base; lower surface and legs paler. 



The keels have very much the same form, being strongly bidentate 

 owing to the deep mesial emargination of the lateral border. The 

 two teeth however are stouter, being less cylindrical and more trian- 

 gular, and the keels themselves are less elevated, giving the back a 

 flatter aspect. 



Copulatory foot very much like that of the, preceding, but the 

 upper terminal process is more abruptly curved backwards, and the 

 lower one less so. 



Length about 52 mm.; width of 10 th somite 6; of 1 st 4.5, length 

 of l"t 2. 



Two male examples. 



53. Platyrhachus inœquidens, sp. n. PL XXII, fig. 1 — l a . 



Sumatra: Manindjau. 



Related to both the preceding species. 



Colour ferrugino-piceous , external half of the keels fia vous; sternal 

 surfaces and legs ochraceous. 



Keels of the first segment smaller, horizontal, taking the form of 

 a pointed tubercle on each side. Those of the second , third and fourth 

 wider than they are long, projecting lightly upwards and becoming 

 gradually more conspicuously bidentate from before backwards. The 

 rest of the keels longer than wide, directed slightly backwards and 

 slightly upwards, the anterior border directed more strongly back- 

 wards than the posterior border, with a distinct shoulder at its base, 

 the lateral border deeply but irregularly excised and consequently 

 bidentate, the two teeth generaly bifid at the apex, subequal in size 

 in the anterior half of the body, but the anterior decreases in size 

 and becomes almost spiniform in the posterior half. The pores situated 



