Melolonthid Genus Ancistrosoma. 431 



ornatis ; capita parvo, rude et conflucnter punctato, oculis haud 

 prominentibus, clypeo brevi, antice fere recto ; pronoto convexo, 

 angolia anticis acutis, posticis obtusis, lateribus medio valde 

 angulatis ; elytris dense punctatis et setosis, vix costatis ; pro- 

 pygidio longo, codem raodo sculpturato, pygidio longo, antice 

 nitirlo, parce punctato, postice crebre punctato et flavo-setoso. 

 Long. 17 rum. ; Jat. max. 6 mm. 



Hub. British Guiana : Mfc. Roraima. 



Although I know only the male of the insect for which 

 this genus is formulated, its characteristics are so peculiar 

 and striking that no other course is possible than to so deal 

 with it, while its close relationship to Ancistrosoma is equally 

 evident. 



Fur. 4. 



Fi"\ 4 a. 



The body is exceedingly elongate and the last two abdo- 

 minal segments are entirely uncovered by the elytra. The 

 middle and hind coxse are widely separated and the thorax 

 and abdomen alike are hollowed out to the full width of 

 their ventral surface. The prosternum forms a conspicuous 

 bifid process behind the front coxse. The whole of the lower 

 surface, with the exception of the last segment of the abdo- 

 men, is clothed with short yellowish hair, which becomes 

 long and thick round the edges of the hollowed surface. 

 The penultimate segment bears a rectangular process directed 

 horizontally backwards. The straight posterior edge of this 

 process bears a row of very short broad bristles, twelve in 

 number, placed in close contact and truncated at the end, 

 presenting the appearance of a set of incisor teeth. This 

 curious comb-like appendage arises beyond the middle of 

 the segment, which is excavated beneath it and projects only 

 a little way beyond its hind margin. The terminal segment 



