176 bulletin: museum of comparative zoology. 



Length cir. 14.5 mm. 



Locality. — State of Amazonas: Manaos! (Mann and Baker). 

 One specimen. ^ 



Otostigmus rex, sp. nov. 



Dorsum, excepting the first plate, dark olive, the plates somewhat 

 paler along the caudal borders. Head and first dorsal plate conspicu- 

 ously and abruptly different in color, being clear brown or somewhat 

 testaceous, the head darker in middle region and in a narrow band 

 running ecto-caudad on each side. Antennae and anal legs conspicu- 

 ously rosaceous in color, the pairs of legs immediately preceding the 

 last more weakly tinged with this color; other legs very pale clear 

 brownish, weakly tinged with greenish. Prosternum clear brown. 

 Venter similar to legs, darkest anteriorly. 



Cephalic plate punctate the punctae very fine and rather weak. 



Antennae composed of seventeen articles of which the first two and 

 a half are glabrous and shining. 



Prosternum with each dental plate bearing a distinctly separated 

 tooth at each ectal end; but with the other teeth thoroughly fused 

 into a continuous plate with no or but obscure traces of the separate 

 ones. The longitudinal sulcus between the two plates of moderate 

 depth. 



Dorsal plates from the sixth on with very fine paired longitudinal 

 sulci extending entire length of plate. From the third plate caudad 

 there are longitudinal depressions mesad of each lateral margin which 

 become deeper in caudal region and thus more sharply separating off 

 the edge or simulating margination. From the third plate caudad a 

 flat median keel is indicated, this on the anterior plates being obscure 

 but posteriorly becoming more distinctly set off by the deepening of 

 the limiting furrows on each side of it. Plates, especially the more 

 caudal ones, rugose in the lateral depressions, the anterior ones other- 

 wise smooth; but the posterior plates, and especially the last five or 

 six, while appearing to the naked eye rather smooth, under the lens 

 are seen to be finely scabrous, bearing over the entire surface, including 

 edges and keel, rows of small, elevated, spinous points. Last dorsal 

 plate bowed out caudad, the extended portion convexly rounded. In 

 front of mesal portion of caudal edge a conspicuous and deep, pit-like, 

 depression from the anterior edge of which a median keel runs cephalad 

 across the plate; surface finely scabrous as on the other plates. 



Ventral plates without longitudinal sulci. From the third or, more 



