CONOCEPHALIN^. 375 



stridulating vein A, forming the vein z', and anastomoses with the first post-axillary 

 vein (z) next to e. (Its direction is indicated by the punctured line.) Moreover, it 

 bifurcates in b; its inner branch (z") forms the second post-axillary vein, which 

 anastomoses with the first post-axillary vein (2), so as to close the central cell (s). 

 This cell is the principal (central or inner) drum ; it is also called the centtal speculum 

 when it is membranaceous. The elongate cell (e) which remains between the anal vein 

 and the first axillary vein is often also membranaceous, and forms the outer drum or 

 speculum. The short vein (c) is only a connection to solidify the stridulating vein and 

 the whole frame of the stridulating apparatus. 



Right elytron (fig. 34). — The right tambourine is covered by the left one, and is 

 generally more membranaceous. Its venation is also more modified to form the ilex (i), 

 on which the stridulating vein of the left tambourine is rubbed to produce musical 

 sounds. On the outer side we find unmodified veins as in the left elytron, the ulnar 

 vein (u) forming the dorsal ridge and the anal vein (a). — The first axillary vein (x) 

 is more oblique than in the left tambourine ; its post-axillary portion (z) forms an 

 angle with its basal portion (x), so that the outer speculum (e) is wider than in the left 

 tambourine. The inner branch (A) of the first post-axillary vein is less transverse than 

 the stridulating vein of the left tambourine. Moreover, the two branches of the second 

 axillary vein do not fuse with the stridulating vein so as to form the anal knot (k) 

 as in the left elytron. 



There is, in fact, no anal knot ; and the stridulating vein is only connected with the 

 second axillary vein by the vein c. The two branches of the second axillary vein (x 1 , x") 

 remain free and form along the inner margin a sort of corneous shell, the ilex (i), on 

 which the musical sounds are generated. If normal, as in the left elytron, the vein x' 

 ought to bend round to form the transverse vein z\ as indicated by the punctured 

 line ; and the vein x" should form the vein z" (inner margin of the speculum) as in 

 fig. 33 ; but the two branches of the second axillary vein (x 1 , x") being broken, and 

 thrown back against the inner margin to form the ilex, are thus separated from their 

 post-axillary portions (z' and z"), so that their homologies are no longer apparent *. 

 The consequence of this modification is that the second post-axillary vein (z"\ being 

 separated from its base (#', x"), fuses with the stridulating vein A ; or, in other words, 

 the vein A is prolonged backwards to replace the normal vein (z") and to close the 

 speculum (s). 



The Conocephalinse principally inhabit Tropical America, very few of them occurring 

 in the United States. The known genera and species of Central America are not 

 numerous. 



* la fig. 34 the vein z' is theoretically the continuation of x', and z" is the continuation of x", as in the 

 left elytron ; but x" being pushed back to the inner margin of the elytron, the vein A is prolonged to replace 

 it, so as to complete the speculum. 



