186 ZOOLOGICAL RESULTS OF THE RUWENZORI EXPEDITION. 



Part I. 



By Gilbert J. Arrow, F.E.S. 



Family Passalid^. 

 DiDYMUS EUWENZORicus AiTow, Trans. Ent. Soc. Lond. 1906, p. 464. 

 Parum depressus, supra ubique minute punctulatus, capite varioloso-rugoso, clypeo 

 fortiter quadridentato, medio minute bidentato, cornu mediano parum prominente, 

 tuberculis posticis distinctis, conicis, carinis frontalibus integris, regulariter 

 arcuatis, angulo acuto convergentibus ; prothoracis lateribus ieviter arcuatis, sat 

 crebre punctatis, angulis anticis fere rectis ; scutello impunctato ; elytris 

 punctato-striatis, punctis dorsalibus subtilibus, lateralibus densis, scalariformibus ; 

 mesosterno glabro, utrinque late foveolato ; metasterni medio impunctato, angulis 

 posticis punctis parvis nonnullis ; abdominis segmentis utrinque triangulariter 

 rugose impressis, segment! ultimi dimidio postico crebre punctato et aureo- 

 hirto. 

 Long. 21-22 mm. Lat. max. 7'5-8 mm. 

 Rab. Mubuku Valley, E. Kuwenzori, 6000-13,000 ft. 

 A series of specimens was collected by the Expedition. 



This species is distinguished by the metasternal plate being quite free from 

 punctures. It is much smaller than JD. kevisternus Arrow, but greatly resembles the 

 West African D. parastictus Imh. It differs from the latter species not only in the 

 unpunctured metasternal disc, but in the rather less acute front angles of the prothorax, 

 the sharply-limited rugose puncturing of the sides of the abdomen, which is confined 

 to definite depressions, the very slight emargination of the last segment and the 

 pilosity of its latter half. 



DiDYMUS CRASSUS Arrow, Trans. Ent. Soc. Lond. 1906, p. 465. 



Ptobustus, sat brevis, modice convexus, capite subtiliter punctato-rugoso, clypeo 

 quadridentato, medio late emarginato, dentibus iBqualibus, carinis frontalibus vix 

 arcuatis, post medium angulatis et tuberculatis, cornu mediano obtuso, postice 

 baud lato aut sulcato, tuberculis posticis transverse carinatis ; prothorace Isevi, 

 medio canaliculato, fossis lateralibus minute punctatis, sulco laterali angusto, 

 paulo punctato, prothorace prseterea impunctato; scutello antice subtiliter 

 punctulato, postice impresso ; elytris striatis, striis lateralibus leviter punctatis, 

 duabus juxta-suturalibus fortiter impressis, tribus intermediis tenuibus ; meso- 

 sterno lato, glbaro, utrinque fortiter foveolato, lateribus punctatis et hirsutis, 



