NO. 2 THORACIC MECHANISM OF A GRASSHOPPER SNODGRASS 9I 



is the flexor sclerite. In addition to the axillaries there are two plates 

 in the median area of the forewing (A, m, m'), and a single median 

 plate in the hind wing (B, m). 



The first axillary intermediates between the edge of the tergum 

 and the second axillary, with each of which it is movably connected, 

 and usually, by an anterior process, it articulates with the base of the 

 subcostal vein. The first axillary is confined to the dorsal membrane 

 of the wing base. In the forewing of Dissosteira the first axillary 

 (fig. 47 A, I Ax) is a flat plate with a narrow anterior process curved 

 outward to meet the base of the subcosta. The sclerite bridges the 

 lateral emargination of the tergum (fig. 22 A, Em) ; its anterior end 

 is supported on the anterior notal wing process (ANP), and its pos- 

 terior part is hinged to the lobe of the scutum (o) behind the emargi- 

 nation ; its oblique outer margin articulates with the second axillary 

 (fig. 47 A). The first axillary of the hind wing of Dissosteira (B, 

 lAx) is exceptional in the reduction of its anterior process which 

 does not meet the base of the subCosta (Sc). 



The second axillary presents an exposed surface in both the dorsal 

 and the ventral membranes of the wing base. Its dorsal part forms 

 a triangular plate (fig. 47 A, B, 2 Ax) lying lateral of the first axillary, 

 and closely hinged to the oblique outer margin of the latter ; its pos- 

 terior outer margin articulates with the proximal median sclerite (m) ; 

 to its anterior end is attached the base of the radius (R). The ventral 

 part of the second axillary forms a strong, concave plate (fig. 48, 

 2Ax) resting by its lower edge on the pleural wing process (IVP). 

 The second axillary dfffers somewhat in shape in the two wings of 

 Dissosteira, as shown in the figures, but its structure and associations 

 are the same in both. 



The third axillary is developed principally in the dorsal wing mem- 

 brane (fig. 47 A, B, 3 Ax), but it includes also a small sclerotization 

 in the ventral membrane (fig. 48, sAx). The dorsal part of the third 

 axillary (fig. 47) has the form of a strong bar extending outward, in 

 the fully-expanded wing, from the small fourth axillary (4AX) to 

 the anal veins, which latter it supports by an arm bent forward from 

 its distal end. The mesal part of the sclerite bears a strong, elevated 

 process on its anterior margin upon which is inserted the flexor muscle 

 of the wing. Distal to the muscle process, the proximal median plate 

 (m) is firmly attached to the third axillary and is functionally a part 

 of it. In the forewing (fig. 47 A) the distal median plate {m') is 

 hinged to the outer margin of the proximal plate. 



