176 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
Length cir. 14.5 mm. 
Locality— State of Amazonas: Mandos! (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 
