RALPH V. CHAMBERLIN 187 



SPIROBOLOIDEA 

 SPIROBOLIDAE 

 Rhinocricus plesius sp. nov. 



Color deep shining black; first tergite narrowly margined anteriorly and 

 posteriorly with brown and the anal tergite similarly margined posteriorly 

 and the anal valves mesally. Antennae and legs light brown. 



Body a very little narrowed caudad from middle and also narrowed 

 slightly cephalad. Metazonites weakly protruding. Scobina detectable 

 back as far as the thirty-sixth segment. 



Head smooth and shining. Sulcus across vertex deep; ending consider- 

 ably above level of antennal sockets. A fine median longitudinal sulcus 

 reappearing between antennae and extending to labrum, becoming more 

 distinct ventrad. A deep foveola each side of median line a little dorsad of 

 margin of labrum and a second, smaller and shallower one farther laterad 

 at very edge of labrum. 



Antennae short as usual, all the articles with the exception of the second 

 as wide as or wider than long. Terminal sensory cones numerous (Group 

 Polyrhabdi of Brolemann) . 



Eyes subtriangular. Ocelli 24 to 27 in 6 series: 5,6,5,4, 3, 1 and 6, 6, 6, 

 4, 3, 2. 



First dorsal plate with anterior margin nearly straight, being but very 

 slightly convex between points near level of lower corners of eyes; below 

 level of eyes the margin is incurved or emarginate and slants obliquely 

 ventrocaudad to the well rounded lateral end. A sharply impressed trans- 

 verse sulcus on each side at about one-fourth the length from caudal margin, 

 this sulcus curving cephalad at ectal end. A second, somewhat obscure and 

 irregular depression parallel with and cephalad from the first. Several 

 short striae extending caudad from anterior margin on each side at or near 

 level of eye. Marked across median region with a considerable number of 

 obscure, irregular, short and fine lines. 



Second tergite extending considerably below ends of the first ; its ventral 

 margin slightly indented at middle of its length, behind which the plate is 

 thickened or somewhat nodular. 



Anterior division of prozonites separated from the posterior by a fine but 

 very distinct circumferential stria, which is a little wavy and which termi- 

 nates on the ventral side at an angle in a transverse stria extending entirely 

 across the prozonite; a transverse stria at level of pore across anterior divi- 

 sion; anterior division marked densely with fine, irregular concentric striae 

 which are fewer toward the caudal division; from the dividing stria above 

 there extend a series of short coarser longitudinal impressed lines. Cau- 

 dal division of prozonite very densely roughened or coriarious, the impres- 

 sions small but deep and the elevations between them narrow and forming a 

 close, irregular reticulation. Metazonitc short, smooth and shining; a 

 series of obscure, short longitudinal imjiressed lines along suture above. 

 Sulcus straight and distinct ; not bent at pore or on some of caudal segments 

 a little angulate. Pore contiguous with or very close to suture. 



TRANS. AM. ENT. SOO., XL. 



