66 MEMOIRS ON THE COLEOPTERA 



take the form of extremely small punctures, the oblique lateral part of 

 the suture obsolete; antennae extending fully to the thoracic base, very 

 slender, the third joint but little longer than the fourth but much longer 

 than the second; prothorax one-half wider than long, the sides evenly 

 rounded, becoming oblique and broadly sinuate basally, the base feebly 

 sinuate, except laterally, very finely margined, the angles slightly 

 obtuse but not evidently rounded; surface feebly convex, smooth, broadly 

 and feebly impressed near each side basally, the impressions with a few 

 punctures; median stria fine, extending only to the obsolete anterior 

 transverse impression, the side margins rather finely reflexed and sub- 

 equally so throughout to the basal angles; elytra oblong-oval, with parallel 

 and broadly arcuate sides, one-half longer than wide, a fifth wider than 

 the prothorax, obtusely ogival at tip, with broad and feeble oblique 

 sinus; striae rather fine and slightly impressed, the scutellar free, moderate, 

 oblique, the second with a discal puncture externally attached at apical 

 fourth; lateral foveae widely spaced medially; abdomen not punctulate; 

 anterior and middle tarsi (cf) dilated and biseriately squamose beneath, 

 the posterior slender, with the first four joints gradually diminishing in 

 length, the first equal in length to the fifth. Length (cf) 9-2 mm.; 

 width 2.5 mm. South Africa (Cape Town). 



I am by no means certain that this species may not have been 

 previously described, but can find no definite reference. If de- 

 scribed, it can be recognized readily from the description. I took 

 the single representative not far from the town more than thirty 

 years ago. 



The presence or absence of so-called opalescent lustre of the 

 integuments is nearly always an important character, usually in 

 fact generic in significance, for this play of prismatic color is due to 

 an exceedingly minute strigilation, forming a true diffraction 

 grating, such as is used for the formation of a light spectrum, while 

 the absence of opalescence indicates that the minute sculpture is 

 of an entirely different order, taking the form of reticulation, when 

 sculpture of any kind is present. 



Opadius n. gen. 



The type of this genus was originally described by LeConte 

 under the name Cratognathus cordatus and was compared with 

 Piosoma, with which it may have somewhat more than a super- 

 ficial affinity, owing to the well developed alternating series of 

 interstitial punctures, only visibly however toward apex, together 

 with a generally compact convex form of body and Cratacanthus- 

 like prothorax. It was subsequently referred by Horn and LeConte 



