1922] Forbes: Wing-Venation of Coleoptera 335 



vaguely defined vein which stiffens the fold half way between the 

 last and the apex in the Gyrinidse, for instance, would then be 5th r. 



There would be possible a second explanation of these veins; namely, 

 that the pivot fold of the Adephaga corresponds not to that of the 

 Hydrophilidas and Tenebrionidas, etc., but to that of the CoccinelHdse 

 and Malachiidas. This would reduce the number of radial cross-veins 

 postulated, as it would make the two main cross-veins of the Adephaga 

 homologous with the two of the Polyphaga, but it would involve a 

 reversal in direction of the two principal transverse folds. It would 

 also leave the faint cells of Hydrous unexplained. This interpretation 

 seems to me less probable, but must be taken into account, considering 

 the variable character of the folding in all parts of the wing. There 

 is much room for some one with care and patience to make a study of 

 the wing folding, which shows much more variety of type than Wood- 

 worth's account would imply. The forms intsrmediate between the 

 Adephaga and Polyphaga (Staphylinoidea in the broad sense; Figs. 

 24 to 28) are all highly modified, and many of them minute, with 

 reduced venation; so that very careful analysis will be necessary to 

 interpret them. 



Between radius and media (as interpreted by the tracheae) the 

 Adephaga have single fully formed cross-vein, marked r-m. In some 

 species of Cupes this has migrated far toward the base of the wing, 

 (Fig. 4), but in other species (Fig. 12), and in Omma, it is normal. 

 In a few Elaters (Fig. 30), it is plainly shown, as a distinct, though faint, 

 vein connecting the base of Rs with M, but as a rule in the Polyphaga 

 it is lost, or incorporated indistinguishably in the radial recurrent. 

 (Compare Hydrocharis, Fig. 22, with Hydrous, Fig. 20). 



The obvious cross-vein of the Polyphaga appears to be a second, 

 the surviving element of a complex net-veined area, apparently, which 

 is faintly visible in some Cerambycidse and Chrysomelidae, but has 

 been mostly obliterated to form the large and complexly folded central 

 cell. Aside from the Phytophaga a few other forms show aberrant 

 veins or thickenings that may be remnants of this system, notably 

 the Cupedidas (Figs. 4, 12) and Ostomidse (Fig. 49). How much is 

 original and how much secondary in the complicated conditions of the 

 Malachiidte (Fig. 5S) and Coccinellidce (Fig. 50) may sometime appear 

 from more detailed study, or the discovery of transitional forms. 



A third radiomedial cross-vein is indicated at the outer boundary 

 of the central cell, connecting the stem or stub of R4+5 with Mi. It 

 must be through the survival of this cross-vein that R2+3 in the Lamelli- 

 corns gets its connection with the medial stem. 



There are two medio-cubital cross- veins, enclosing the so-called 

 Oblong cell (O) of the Adephaga and Cupedidae. The more basal of 

 these may receive a trachea from media, but I am inclined to consider 

 this not significant, as the assumption that it is really the stem of 

 M3_,_4 will not work out into any logical interpretation of the marginal 

 veins. In the more specialized Adephaga (Fig. 13) and the Hydro- 

 philidae there is only one cross- vein. The usual explanation is that 

 one or the other has atrophied. It seems more simple to assume the 



