106 EAST AFRICAN POLYDESMOIDEA— COOK. vol. xviii. 



First segment short, slightly bisinuate in front, more strongly tri» 

 sinuate behind; posteriorly broader, the posterior corners sharply 

 pointed and decurved; submarginal ridge like that of the following 

 segments, its interior edge sharply defined. 



First four segments: the tubercles lying along the median line are 

 very different from the others, which appear small and irregularly dis- 

 tributed, and are conspicuously large and arranged in two longitudinal 

 rows, three (tubercles) in each row. Those of the first segment are 

 lower and isolated, those of the two following coalesce into two dentate 

 ridges, those of the fourth segment highest. 



Subsequent segments ornamented with three transverse regular rows 

 of tubercles; those of the posterior rovf more mammilliform, higher, and 

 the remainder of the surface finely granulated. 



Lateral carinte projecting above the lateral middle of the body, dis- 

 tinctly, though not strongly ascending, slightly higher caudad; the 

 margins usually with five or six teeth; the first and second segments 

 with three sharp teeth, the third with four; posterior corner on middle 

 segments slightly angled, on the three segments next to the last with a 

 gradually more prominent dentiform process. 



Last segment above granular rugulose, posteriorly with a quadran- 

 gular process, rounded at apex, and on each side with three teeth, 

 notched between ; above, on each side, a wart-like tubercle. 



Preanal scale with two blunt-conic setiferous tubercles; between 

 them a shorter process. 



Color reddish-brown, the tubercles ferruginous or yellowish; margin 

 of carina? yellow or light ferruginous. Clypeus on either side ferrugi- 

 nous in the middle, with a broader yellow margin ; ventral surface ferru- 

 ginous. Antennfe ferruginous, the apex brownish. Legs ferruginous 

 yellow. 



Length, 44-47 mm.; width, 6^6| mm. 



Locality. — Two female specimens from Mombassa. 



The types of this species are dried specimens, preserved in the Berlin 

 Museum, belonging to two distinct species. The following notes were 

 based on the specimen, to which Gerstacker evidently gave the most 

 of his attention, and which was the subject of his plate. The other 

 species is here described as 0. unicolor: 



Vertex prominent hirsute, granular rugose. 



Clypeus, as described for Mcolor, rather smooth, hirsute, especially 

 below. 



First segment shaped as in PI. V, fig. 12, but more emarginate pos- 

 teriorly toward the lateral corners; tubercles in three rows, stronger 

 than in fig. 12, especially the median. Eows 4, 6, 6, situated somewhat 

 as in fig. 12, but the median tubercles wide apart; also those of pos- 

 terior row, which are large, conico-ijapilliform. Margin more coarsely 

 dentate than in 0. bicolor. 



Second and third segments also with all the median tubercles wide 

 apart, much larger than the others, the posterior largest, and all three 



