310 THE WINGS OF TRICHOPTERA 



in the margin of the wing near the tip of the first anal vein. A third branch 

 of the third anal vein supports the margin of the posterior lobe of the wing, 

 the fibula. In some species of Rhyacophila the terminal portion of this 

 third branch of the third anal vein extends across the fibula to the axillary- 

 furrow. 



The disposition of the anal veins of the fore wings is one of the most 

 distinctive characteristics of the order Trichoptera. 



In the hind wing the subcosta resembles the subcosta of the fore wing 

 except that it bears no accessory vein. The radius also resembles the 

 corresponding vein of the fore wing. The media is only three-branched, 

 veins M3 and M4 coalescing to the margin of the wing. The cross-vein 

 connecting media and cubitus near the base of the wing, the posterior 

 arculus, is transverse. Veins Cu and ist A coalesce at the base of the wing 

 for a much shorter distance than in the fore wing. The anal A-eins differ 

 from those of the fore wing in that they all end separately in the margin of 

 the wing. 



There is one feature in the disposition of the anal veins of the hind wing 

 which, like the coalescence of the tips of anal veins in the fore wing, is a 

 distinctively ordinal characteristic; this is the course of the second anal 

 vein. This vein, near the base of the wing, extends forward until it reaches 

 the first anal vein, with which it anastomoses for a considerable distance; 

 it then bends away from the first anal vein abruptly and extends obliquely 

 until it is joined by a cross-vein, it then bends again and extends longitudin- 

 ally to the margin of the wing. The cross-vein connecting the second and 

 third anal veins is nearly longitudinal. 



The interpretation of the homologies of the wing-veins given above 

 differs in one respect from that which has been commonly accepted. This 

 is the recognition of the fact that in the fore wings veins Cu and ist A 

 coalesce at the base of the wing and what appears to be an oblique cross- 

 vein between veins Cu and ist A is really the base of the free part of vein Cu. 



This conclusion does not necessitate any change of view regarding the 

 homologies of the terminal portions of cubitus and the first anal vein ; con- 

 sequently the lettering of figures of wings that is placed at the tips of veins 

 will remain as before. 



The necessity for reopening the question of the homologies of the wing- 

 veins of the Trichoptera was suggested by Dr. Cornelius Betten, who 

 reached the conclusion that the vein designated here as vein Cu -|- i st A is 

 the cubitus and that designated as the first anal vein is vein Cu2. This 

 necessitated the conclusion that what heretofore has been regarded as vein 

 Cu2, and which I still believe to be this vein, is a definitive accessory- vein, 

 which Dr. Betten terms vein Cuia- 



Although Dr. Betten's discussion of this question is not yet published, 

 he has ptiblished a figure in which the veins of the fore wing of a species of 



