BY R. J. TILLYARD. 277 



Of all the fossils so far found at Ipswich, this wing is perhaps the most 

 perfectly preserved as regards the minute structure of the veins and membrane. 



Mesogereon compressum, u.sp. (Text-fig. 68.) 



A nearly complete but very poorly preserved forewing, in which the longi- 

 tudinal veins have been compressed together to some extent, especially from 

 the costa down to M3. Greatest length, 42 mm., representing a total length of 

 about 45 mm. Greatest breadth, only 8 mm., representing a true wing-breadth of 

 about 12 mm. 



The extreme base of this wing is missing, owing to a diagonal break from 

 near the base of m-cu up to and including the first fork of M. The whole of the 

 clavus is absent, and also a narrow strip along the termen, including the coriaceous 

 border. Text-fig. 68 shows a portion of the wing, including the cross-vein r-m 

 and the forks of M1-2, Ma -4 and Cm. The cross-vein r-ni is very short, each 

 of the two main veins Rs and Mi being curved in slightly at this point, and then 

 diverging slightly again distad. As a result of compression, together with, per- 



Text-fig. 68. — Mesogereon fOw/>r<'M«/«, n.sp. Details of venation of forewing. (x 6|). 



haps, a longitudinal split, the space between M2 and Ms has become greatly 

 lessened ; and Ma , lying at a lower level than M2 on the rock surface, disappears 

 under the slight ridge on which this latter vein lies. Distance between fork of 

 Mi-3 and fork of M3-4, 2.9 mm. (possibly a little more in the uncompressed wing) ; 

 length of basal piece of M4, 0.6 mm. Cross-ridges clearly marked, tuberculation 

 weak. 



Type, Specimen No. 144a, in Coll. Queensland Gcul. Survey, Brisbane, t^. 

 Type-counterpart, specimen No. 1446, in same collection. 



Horizon, Upper Triassic, Ipswich, Q. 



Mesogereon- appine, n.sp. (Text-figs. 69, 70, Plates xix., xx.. Figs. 21, 22.) 



Specimen No. 206a represents a nearly complete forewing with most of the 

 termen missing, and with all four branches of M broken along an oblique line in 

 the distal part of the wing, so that their distal ends bend downwards at a well 

 marked angle. Greatest length of fragment, 35 mm., representing a total length 

 of wing of about 40 mm. Greatest breadth, 11.5 mm., representing a total 

 width of about 12 mm. 



Text-fig. 69 shows the well preserved basal portion of this wing, excluding 

 the clavus. A small round hole made by a sharp instrument near the base of 

 R is indicated by the finely dotted circle. It will be seen that the origin of 



