1901.] MYIUAPOIU OF THE " SKEAT EXPEDITION." 509 



].st tergite. Differs much from the others, it is longer than the 

 head, roughly semicircular in shape, uot so broad as the others, 

 and without keels ; it is covered with large wart-like tubercles and 

 smaller granules. The larger tubercles are arranged in two groups, 

 so as to leave a clear space free in the direction of the longitudinal 

 furrow. 



'2n<J tergite. Prolonged into two keels, which are, however, shorter 

 than the succeeding ones. Like the first tergite it shows a dis- 

 position to be tuberculated, as in addition to the two dorsal tubercles 

 which enclose the dorsal furrow there are a number of smaller 

 tubercles near the large ones. This arrangement of the tubercles 

 forms an interesting gradation between the third tergite, smooth 

 but for the two large dorsal tubercles, and the first tergite with its 

 two groups of tubercles arranged in the same position as the two 

 dorsal ones in the other somites. 



The remainder of the somites resemble one another closely. 

 The keels are long and bluntly pointed, the posterior angle being 

 the most acute ; they cover the short legs completely. The shape 

 of the body rises with a steep slope to the back, where there are 

 two large tubercles with a wide depressed space between them, 

 along which there runs a deep longitudinal furrow. Each tubercle 

 has a small tubercle projecting from its base (pores '?). The bases 

 of the legs are close together and are attached to a free sternal 

 plate. Outside the legs are the spiracles, each on a small tubercle. 

 The median dorsal furrow is continued right up to the tail, and 

 the dorsal tubercles, though smaller in the last two somites, are 

 still present. 



Sub-Order Polydesmoidea, Pocock. 



Family Polydesmid.e. 



Genus Platyehacus C. Koch. 



Platybhacts itumbehti, var. nov. (Plate XXX. figs. 10-13, 15.) 



Label : " Gunong Inas, Perak. A scent of HNC. The palest 

 coloured of the three largest specimens squirted out fluid from 

 inter-segmental pores ; all emitted." 



Thei'e are three female specimens of this species, all from the 

 same locality, and differing considerably in size and colour. 1 have 

 no doubt that they are a variety of the species described by Pocock 

 as humberti, but as they do not correspond exactly, 1 will give a 

 full description. 



Length K»7 mm., greatest breadth 1-1 mm. 



Body narrowed ulteriorly and posteriorly. 



Colour very deep chocolate, extreme edges of keels and of anal 

 plate flavous. Legs and sterna same chocolate-colour but lighter. 



Head thickly granular; shallow frontal furrow ; upper lip with 

 row of bristles, each proceeding from a small tubercle. 



IgtUrgitt slightly wider than head, the lateral contour of the 

 Pboi . Zooi. Soc— -1901, Vol. II. No. XXX I V. :'.l 



