1Q MONOPLATUS. 



Oblong-ovate, subparallel, subde pressed, minutely punctate-striate, 

 glabrous, ferrugineo-rufous. Head short, depressed, very slightly 

 produced ; above the labrum is a transverse linear depression; im- 

 mediately above the base of the antenna; is a transverse depression 

 which gives a prominence to two obsolete oblique elevations between 

 the eyes, forming together (broadly, and at an obtuse angle) the 

 character of the letter V ; eyes large, globose, prominent, situated at 

 the base of the head, extending laterally as far as the anterior angles 

 of the thorax ; the surface at the base of the head impunctate and 

 glabrous. Thorax transverse, rectangular, slightly constricted at 

 the base, hardly emarginate in the front ; the anterior angles are de- 

 pressed and subacute, the sides marginate ; parallel to the basal line 

 is a well-defined transverse fovea, which terminates abruptly before 

 it reaches the sides by being deflected into the Hue of the base ; 

 the surface is impunctate, ferrugineo-rufous, clouded sparingly and 

 minutely with fuscous. Scutellum triangular, impunctate, rufous. 

 Elytra broader than the thorax, robust, subparallel, very faintly 

 punctate-striate (the striae being almost obsolete, and the punc- 

 tures frequent and very minute) : from the humeral angles extend 

 two longitudinal carinations parallel to the margination, one between 

 the eighth and ninth, the other at the eleventh stria ; these carina- 

 tions become obsolete as they approach the apex ; an antemedial 

 depression extends transversely as far as the first carination, which 

 (when viewed laterally) gives an appearance of prominence to the 

 surface near the scutellum : the antemedial elytra are in colour 

 ferrugineo-rufous, clouded minutely and sparingly with fuscous ; the 

 apical portion of the surface is dark cyaneous ; the line of demarca- 

 tion being somewhat antemedially transverse, and falling away ob- 

 liquely towards the apex as it approaches the line of margination. 

 Antennas long, filiform, of a dark fuscous colour, the three basal 

 joints being rufous. Legs flavo-rufous throughout. 



In one of the examples of this species, the azure-blue of the apical 

 half of the elytra is represented by black, the anterior tibia; and tarsi 

 also being black. 



This species, and those immediately allied to it, approach in co- 

 louring to M. apieatus. Of the latter, the apex only (that is, hardly 

 one line of the 2\ lines — the length of the elytra) is black : in M. 

 semiclialybeus, more than half of the elytra is deep azure or black 

 (that is, 1\ line of 21— the length of the elytra). This distinction 

 obtains so exactly and so uniformly in the different examples of 

 either modification of colouring (of which I have both sexes), that of 

 itself (without any reference to well-defined though minute structural 



