42 



INTRODUCTION. 



at the base to any other vein. This is a very distinct and 

 uniform type, as far as it goes, but its adoption seems to 

 have the effect of keeping apart several genera that on other 

 characters appear to be somewhat closely allied ; this kind 

 of difficulty, however, is liable to arise in every system of 

 classification. 



3. Cantharid or Tdepliorid type (fig. 20). — The chief characteristic 

 of this division is the loop formed at some distance from the 

 apex of the w T iugs by the coalescence of the two median veins, 

 one alone (it is usually hard to say which) being continued to 

 the margin from the centre of the loop. A somewhat similar 

 loop is found in the typical species at the apex of the radial 

 veins, and transverse veins occur joining the cubital and anal 

 veins ; in all these forms, however, there is great variation, 

 and the type, as a whole, undergoes so much modification, 

 and sometimes breaks down so entirely that its value becomes 

 very doubtful. The characteristic median loop is very small 

 in some families, and is often reduced to a mere hook at 

 the apex (as in Tegrodera erosa, one of the Melold^e).; 

 it is very plain in many Lamellicorns, but practically absent 

 in Geotnipes, and this is also the case with the Passalid^e and 

 many Rhynchophoiia. Many of these latter, with their quite 

 simple venatiou and the absence of any transverse veins, might 

 well be classed under the Staphylinid type. This variation 

 largely discounts the value of the whole characters of the wing 

 venation as affording a reliable ground for classification ; at 

 the same time it is a very great help if taken in conjunction 

 with other characters. 



A beetle may be compared to an aeroplane, being considerably 

 heavier than air, with the elytra and wings constituting the 

 balancing - frame, the body representing the passengers and 

 material, and the wing-muscles representing the motor. In order 

 to counteract the comparatively great weight of the body the 

 wings must present a correspondingly large area, and must, 

 therefore, when expanded, be much larger than the elytra. As 

 it is, however, of the greatest importance to the insect that the 

 delicate wings should be protected by the elytra, there must neces- 

 sarily be a mechanism for folding them, and this we find to be the 

 case not only in the Coleoptera, but in all orders that have the 

 outer wings corneous or coriaceous ; the arrangement is especially 

 simple and beautiful in the case of the PonFicuuiDiE and Blattid^e, 

 in which the wings open and shut like a fan. This is also seen in 

 the Phasmid.e. In the Coleoptera the method of folding is both 

 longitudinal and vertical ; in many cases the apical and anal 

 portions are singly or doubly folded back upon the rest of the 

 wing, but in other cases, especially, as might be expected, in the 

 brachelytrous species, the arrangement is much more complicated. 

 We have received a valuable paper from Mr. Woolworth, published 

 by him in the ' University of Canada Publications ' (Technical 



