INTRODUCTION. i> 



ancient unmodified wings partly persist, six elevated ribs or 

 nervures containing the main tracheae and other vessels are 

 plainly visible, one running along each margin of the wing and 

 four between and parallel to them. In many species of Adoretus^ 

 Anomala, etc., as well as in the DYNASTIES and other groups, a 

 practically identical condition is seen in the mature state, the six 

 ribs being divided by the humeral callus or shoulder prominence 

 into an inner and outer series of three, and separated by broader 

 intervals which generally diminish from the inner to the outer 

 margin (fig. 3, a). The two innermost and broadest of these 

 intervals are dorsal, the third is continuous with the shoulder 

 prominence, and the two outermost intervals are lateral and more 

 or less perpendicular. These lateral costae and intervals are 

 generally crowded together and show few distinct differential 

 characters, and it is sufficient to examine those which lie between 

 the sutural or inner edge and the shoulder, i. e. those here called 

 the dorsal spaces. The six elevated ribs, called the primary 



Fig. 3. Eight elytron, to show types of sculpture : a, primitive condition - 

 b, intermediate condition ; c, advanced condition ; d, humeral callus. 



costse, are counted from the inner edge of the elytron, the first 

 being also known as the sutural costa and the third as the iutra- 

 humeral. The primary costse are generally emphasised by a line 

 of punctures bordering them on each side, sometimes united 

 into a continuous groove, and the punctures or grooves often 

 remain when the costae have disappeared as elevations above the 

 general level. The appearance of a line of punctures, more or 

 less regular and complete, along the middle of each of the 

 intervals (or at least of the inner ones) separating the primary 

 costa?, forms the next and most common stage in the EUTELIN^ 

 (fig. 3, b). These secondary lines are often so far developed as 

 to be practically indistinguishable from those which outline 

 the primary costa?, so that seven similar and equidistant lines 

 appear between suture and shoulder instead of five unequally 

 spaced ones (tig. 3, c;. Earelv, as in some species of Parastasia, 

 the lines vanish almost completely, leaving the surface smooth,, 

 but the lines which indicate the primary costao are more persistent 



