448 MESOZOIC IXSECTS OF (QUEENSLAND, ix., 



a large portion of the wing. Taken together, they enable us to eomplete the 

 restoration of the wing, the only parts not found upon one or other of the 

 fragments being a portion of the distal area below the apex, together with the 

 apical border itself, part of the distal branching of the cubitus, and the actual 

 outline of the anal border. A study of all the specimens discovered shows that 

 the original interpretation of the venation given by me was incorrect. A new 

 definition of the family and genus is here given : — 



Family Mesorthopteridae : Large Protorthopterous insects having rather long 

 wings, well rounded at the apex, and carrying numerous main veins separated 

 everywhere by a eomplete archedietyon or original meshwork of irregular poly- 

 gonal cellules, as shown in Plate li., flg. 26. Costal space with many oblique 

 veinlets. Sc a strongly formed vein. R strongly formed, with the origin of Rs 

 placed far from base. M a weak vein fused with R basally and diverging only 

 slightly from it. Cui a very strongly formed vein, giving off a series of numerous 

 anterior branches. Anal area rather narrow. 



Genus Mesorthopteron Till. (Plate li., flg. 26; Text-fig. 72.) 



Large insects having the forewing somewhat longer and narrower than the 

 hind. Sc long, reaching to about one-fifth from apex, and with the subcostal 

 veinlets evenly spaced and mostly unbranched. Ri branching apically so as to 

 fill the space between end of Sc and apex of wing. Rs with few branches, all 

 running to margin around apex. Mi-1-2 with few branches, Ms -1-4 a weak furrow 

 vein without any branches at all. Main stem of Cui giving off anteriorly a series 

 of about six anterior branches, very regularly arranged, most of which fork 

 dichotomically before reaching the margin; the branches of this vein supply a 

 space reaching from just below the apex right round to half-way along the pos- 

 terior margin. Cu2 a weak, straight, furrow vein, ending up somewhat before 

 half-way along the posterior margin. Apparently only two anal veins, the first 

 running parallel to Cu2 just below it, and probably branched distally, the second 

 somewhat curved, with a number of descending branchlets. In the costal and 

 anal areas the archedietyon is much denser than on the rest of the wing, being 

 formed of a very large number of very irregular cellules; in the rest of tlie 

 wing, it consists chiefly of two rows of polygonal cells lying between each 

 consecutive pair of longitudinal veins. 



Genotype, Mesorthopteron locustoides Till. 



The genus remains monotypic, and can be recognised at once by the extra- 

 ordinary manner of branching of Cui, which, as far as I know, is unique within 

 the Class Insecta. Small fragments of the wings of this insect are frequently 

 met with at Ipswich, and can always be recognised by the very characteristic 

 archedietyon. 



Mesorthopteron locustoides Till. (Plate li., flg. 26; Text-fig. 72.) 



The restoration of this fine wing, given in Text-fig. 72, is based chiefly upon 

 Specimen No. 2586, a large fragment of a forewing, showing almost the whole 

 of the costal margin (except the apical and basal portions), and portions of all 

 the veins down to within a short distance of the posterior margin; the latter, 

 together with the anal area, is absent. Total length of fragment, 22.5 mm., from 

 which the measurements of the complete forewing may be estimated to be about 

 35 mm. long by 15 mm. wide. 



The other fragments studied in making the restoration were the following: — 

 Specimen No. 72 a-b : a small piece, showing portion of the anal veins and 



CU2. 



