218 OETHOPTEEA. 



and for all the nervures of the tympanum. After having thus been fused together, 

 the three nerves separate again and become longitudinal. The v. post-analis (a 1 ) is 

 the continuation of the v. analis (stridulans) ; it is often united to the v. diagonalis 

 or to the speculum by from 1-3 venulae. The first and second v. post-axillares (s, z\ 

 fig. 9) are the continuation of the first two venoe axillares (#, a/, fig. 22). The third 

 v. axillaris (x") is not deflexed like the preceding veins, but becomes quite marginal (z"), 

 and extends along the sutural margin of the elytron ; before it reaches the anal knot 

 it is somewhat thickened and forms the inner margin of a sort of conchoid excavation, 

 the latter being more or less corneous, but with a small membranous area. This 

 peculiar organ, called by Goureau chanterelle {illeoc), is the generator of the sounds, 

 as proved by the fact that it is on its margin that the archet rubs and produces the 

 vibrations, which, through the anal knot, are carried to the nerves of the whole 

 tambourine. The little musical field is of a different form : it is much developed and 

 conchoid in the Gryllinse, but becomes very narrow and but slightly apparent in the 

 Eneopterinse *. 



The vena diagonalis (b) has a less evident homology. It must be identified 

 with the v. ulnaris, by supposing that it has been deflexed and broken angularly 

 together with the v. analis. Indeed, the proximal part of this vein, pressed against 

 the v. analis, has disappeared, and seems to have fused with the vena stridulans^, 

 so as to make this thicker and more robust ; and it only emerges again before the knot. 

 The v. diagonalis is a strong vein, supporting the speculum (s), which is an important 

 drum. 



The speculum (figg. 9, 21, s) results from the bifurcation of the diagonal vein. Its 

 outer margin (V) is formed by the apical part of this vein, which posteriorly curves 

 into an elliptic form. Its inner margin is formed by the first branch of the diagonal 

 vein, which joins the end of the nerve of the outer margin (d), so as to close the field. 

 The speculum is parted transversely by a second branch of the v. diagonalis, sometimes 

 by two branches; in rare cases by numerous branches of arched form (Tab. XII. 

 fig. 4). The speculum as described is anteriorly angulate (fig. 21), but often takes 

 an ovate form (fig. 9) ; its outer angle is anastomosed with the v. media (m) to form 

 the stigma (I). The vence post-analis (a') and post-axillares (z, z') anastomose together 

 at their extremities (fig. 9), forming closed elongate cells. The vena involvens (fig. 9,i) 

 is very irregular. It may be formed by the prolongation of the v. media (m) through 



* If the v. stridulans is to be compared to a fiddle-bow, the 3rd v. aocillaris (%") on which the bow rubs, 

 and also the vence jaost-analis and post-aceillares emerging from the anal knot, should be compared to the 

 chords or strings of the instrument. Nevertheless, I must abandon the term chords or strings in order to 

 avoid confusion. 



f This appears to me to be the more certain, as in the females the ulnar vein has often a common origin 

 with the anal vein (figg. 6, 18). 



