14 Mr. C. 0. Waterhouse on 



Aulacosteihus Arclieri, sp. nov. (PI. III. fig. 1) . 



$. Niger, sub-opacus; niaiidibulis elongatis, intus 

 bidentatis ; capite subquadrato, depresso^ antice 

 contractOj fronte excavata, lateribus fortiter rugoso- 

 punctatis ; oculis omuino a cantlio divisis; thorace 

 transverso, lateribus sub-rectis, angulis posticis 

 oblique truncatis, marginibus anterioribus et poster- 

 ioribus elytrorumque basi rugoso-punctatis ; tibiis 

 anticis apicibus fortiter bidentatis, et extus denticulis 

 quatuor armatis ; tibiis posticis extus in medio uni- 

 dentatis, apicibus singulariter ampliatis; prosterno 

 longitudinaliter carinato. 



Long, (mandibulis exclusis) 17^ liu. (37 mill.); man- 

 dib. 1\ lin. (16 mill.). 



Black, somewhat dull. Head flattened, one quarter as 

 broad again as long, slightly narrowed towards the front 

 to the insertion of the antenna, then suddenly contracted, 

 forehead excavated, projecting over the clypeus, which 

 is transverse and gently emarginate ; the head is con- 

 tracted posteriorly to be received into the thoi"ax, the 

 posterior mai'gin and the portions over the base of the 

 mandibles shining, the rest of the surface rendered dull 

 by extremely tine granulations, on the disc there are a 

 few larger punctures, and towards the sides and the parts 

 about the eyes punctured, a patch reaching from the eyes 

 almost to the posterior angles of the head, very rugosely 

 punctured. Mandibles about equal in length to the head 

 and thorax together, very gently curved, with a large 

 blunt tooth springing froin the upper surface, distant 

 from the base about one third the length of the mandible, 

 another smaller tooth, also springing from the upper 

 surface, being situate near the apex of the mandible, 

 gives it the appeai^ance of being bifid. Mentum twice and 

 a half as broad as long, slightly convex, with the basal 

 portion in the middle depressed ; rounded in front, the 

 posterior angles rounded, slightly overlapping the sub- 

 mentum, the whole surface coarsely transversely reticulate. 

 The 8th, 9th, and 10th joints of the antennee forming the 

 club, the 8th joint half spongy, the 9th and 10th entirely 

 so. Thorax twice as broad as long, posterior angles 

 obliquely truncate in front, bis-emarginate ; sides rounded 

 at the anterior angles, gently contracted posteriorly, and 

 again projecting at the truncature of the angles, posterior 



