14 



Illinois, U.S.A. It is definite evidence that, even as early as Mesozoic 

 times, Australia was a sanctuary for archaic forms which probably 

 had died out long before in the Northern Hemisphere. 



Order PROTORTHOPTERA. 

 GENUS MESORTHOPTERON, gen. nov. 



Forewing narrower than hindwing, very densely veined, and 

 slightly thickened, probably forming a weak tegmen. Hindwing 

 not thickened, membranous, hyaline, with less dense venation. 

 Subcosta is a fairly strong straight vein, sending off a series of obliquely 

 placed parallel cross-veins into the fairly wide costal space above it. 

 Radius forms a very strongly built vein lying fairly close beloAv the 

 subcosta, and giving off posteriorly at least one branch, the radial 

 sector (Rs). Median vein slenderer, giving off before the level of the 

 origin of Rs at least three branches anteriorly from the main stem, the 

 first two of these arching slightly upwards towards R. Cubitus 

 branched in forewing, possibly unbranched in hmdwing. Several 

 anal veins present in hindwing. 



TYPE : Mesorthopteron locustoides, sp. nov. 



MESORTHOPTERON LOCUSTOIDES, sp. nov. 

 Plate 1, fig. 4, and Plate 2, figs. 3-6. 



This species is represented by three fragments, two of which 

 (Plate 2, figs. 3, 4 5, 6) are very similar in shape, and represent 

 closely similar portions of the left hind and fore wing respectively. 

 The third piece (Plate 1, fig. 4) is a slightly smaller fragment from a 

 more distal part of a hindwing. Had it not been found close to the 

 other two, there would be little to connect it with them, but it seems 

 to be undoubtedly a portion of the same insect. 



The fragment labelled 5a (Plate 2, fig. 5) and that labelled 56 

 (Plate 2, fig. 3), when compared together, are seen to differ in three 

 important particulars : (1) The fragment 5b is a much lighter and 

 more delicate impression, scarcely raised at all above the rock level 

 on which it is placed, Avhereas 5a is more distinct, and appears to 

 represent definitely a wing of thicker substance ; (2) the former 

 shows little trace of cross-veins, whereas the latter is covered by a 

 dense network of small cells, except in the costal space ; (3) judging 

 by the amount of divergence of the main veins, 5b was a broader 

 wing than 5a. All these three facts point definitely to specimen 5a 

 being the foreAving and specimen 56 the hindwing. The thicker 

 texture and denser venation of 5a suggests at once that this forewing 



