31 



the small arm distally on M, mentioned above, and (3) a slight 

 straightening of Sc at the oblique distal cross-vein. It appears, 

 therefore, that Mesochorista is undoubtedly the ancestor of T cenio- 

 chorista, and we can only marvel at the slightness of the change 

 through such long ages. The persistence of the five costal cross-veins 

 in the same position for so long a time seems to be an extraordinary 

 case of the survival of comparatively useless structures ; the middle 

 three, at any rate, appear to be quite useless. The allied genus 

 Chorista has no cross-veins in this space, but the costa is more strongly 

 arched. Chorista is also aquatic, and may well represent another 

 line of descent from a form very close to Mesochorista, but with 

 stronger cross-veins. 



MEASUREMENTS : Greatest length of fragment 10.5 mm., 

 breadth 4 mm. The forewing of T ' ceniochorista pallida is 16 mm. 

 long ; that of Mesochorista appears to have been, about 13 mm. in 

 aH. 



TYPE : Spec. 32 (Plate 2, fig. 2). TYPE-COUNTERPART : 

 Spec. 326. (B. D. Coll.) 



OBS. : A consideration of the characters to be observed in this 

 interesting fossil offers very definite evidence of the stability of 

 aquatic or semi-aquatic life in the region of Southern Queensland 

 from the Trias to recent times, and helps us to understand how it 

 was that Ceratodus also remained unchanged and unmolested in this 

 same area. It should be added that specimens of T ceniochorista are 

 exceedingly rare, and nothing is known of their life histories, except 

 that they are aquatic or semi-aquatic. 



Order LEPIDOPTERA. 

 Family DUNSTANIID/E. 

 Genus DUNSTANIA, gen. iiov. 



HINDWING. Very broad, surrounded by a wide margin without 

 pits. All the rest of the wing-membrane, between the veins, densely 

 pitted all over ; these pits appear to represent the bases of insertion 

 of the wing-scales, which are completely lost. Subcosta waved, 

 reaching the anterior border at a distance of one-fifth of the wing 

 length from the apex. Upper branch of radius waved, ending at 

 apex. Basal cell (d^) formed between radius and media, narrow, 

 elongate, with short distal side somewhat weakly formed. Beginning 

 above the distal end of this cell, and extending distally from it, is a 

 larger second cell (cL), narrow, biit increasing in width distally until 

 near its apex, where the enclosing veins curve gracefully in to meet 

 at an angle. From this angle a single vein runs to the termen well 



