336 Annal^ Entomological Society of America [Vol. XV, 



two have fused, especially as in several Carabid^ there is a partial 

 fusion. The families in which there is a single cross-vein are the 

 Cicindelidas (save the genus Pogonostoma, as figured by Horn, Gen. 

 Ins., 82, pi. ,5, f. 52), R,|iysodidce and Hydrophilidae, with a few stray 

 genera of other families. In the remaining Polyphaga the cross- veins 

 are obliterated by the fusion of M4 with Cu. 



The cross- vein cu-lst a is mentioned under the discussion of that 

 vein. In Cupes alone there is a second cubito-anal cross-vein in the 

 outer part of the wing; ; , - 



■ : A very' 'impoirtant''ci*Oss- vein is the one from the base of 1st A or 

 from the fused root of Cu^-lst A to the base of 2d A. It is doubtless 

 homologous to the anal cross- vein of the Trichoptera and lower Lepi- 

 doptera. ' In all forms but the Cupedidae the extreme base of 1st A 

 is transverse and appears (with the disappearance of a sector of 1st A) 

 as a part of it. I will refer to this combined vein as the anal arculus 

 (a. arc.) as its relation to 1st A is exactly that of the arculus to media 

 in the Odonata and some other orders. This vein appears in all the 

 Adephaga and Staphylinoidea, excluding the Histeridge, but nowhere 

 else. Another cross-vein lst-2d a appears in the outer part of the wing 

 in Cupes oculatus (Fig. 12), but in most other Coleoptera it is obliterated 

 by the anastomosis of the anterior branch of 2d A with 1st A. 



Two cross-veins may be assumed between 2d A and 3d A, enclosing 

 the wedge-cell (W) between them, but as noted in the discussion of 

 2d A, it is not quite certain that the inner is a cross-vein, and the 

 outer is preserved only in the Elateridge, Lampyridse, and a few related 

 forms. 



There is in the Cupedidae and Adephaga a transverse vein at the 

 extreme base between 3d A and 4th A, but its significance is uncertain. 



• - FOLDING. 



I figure folding diagrams of a few typical Coleoptera (Figs. 7, 16, 

 21, 25, 27, 61). In these the portions of the wing reversed (turned 

 under or over) in the folded wing are shown dark, those which remain 

 right side up are white. Convex folds are indicated by a broken or 

 serrate line, concave by an even line. Regions of irregular crumphng, 

 and regions not completely folded under, are striated. 



It can be seen that the folding is highly complex, and may differ 

 in details in closely related forms, though of the same fundamental 

 plan (compare especially Harpalus, Fig. 16, with Dytiscus, Fig. 7). 

 The Dytiscid and Hydrophilid foldings are homologized by d'Orchymont 

 differently than by me, with the result that he considers the vein I 

 call media in the Adephaga to be rather the radial recurrent. I have 

 given first weight to the fact it always contains the medial trachea, 

 and have assumed that the area at the hinge that folds under has become 

 more extensive in the Adephaga, and has crossed the medial vein. 

 It should be also noted that the area homologous with the reversed 

 portion in the cell of the Adephaga is not the large reversed portion 

 of the Polyphaga, but the relatively inconspicuous crumpled strip 



