161 



MEGATOMA. 



I have before me an example from N. Queensland which must 

 be referred to this genus. It is undoubtedly very close to 

 M. ietiuifasciata, Reitt., which appears to be the only Aus- 

 traliaa Megatoma hitherto described. The only objection I find 

 to its identity with Reitter's species consists in its narrow elytral 

 fascia being of zig-zag form, whereas Reitter calls it " Subrecta." 



This poiLts to the probability of its being a distinct species a 



probability increased by the remoteness from Queensland of 

 Tasmania (Reitter's locality). Unfortunately my specimen is 

 not in sufficiently good condition for me to be able to describe it 

 satisfactorily. 



TROGODERMA. 



To a casual glance most of the Australian species of this genus 

 appear scarcely distinguishable inter se, but a careful examination 

 of their structure shows them to possess particulary satisfactory 

 differential characters — chiefly in the antennae and theprosternal 

 sulci. I have found the latter to be the organs on which it is 

 most convenient to base the primary divisions of the genus. 

 These sulci are cavities for the reception of the antennge in repose 

 and always run the whole length of the prosternum immediately 

 within its lateral margin on either side. Consequently the varia- 

 tions in the form of the sulci result from the nature of their 

 inner and kind margins, In what seems to me the most highly 

 developed form the sulci are very deep and narrow, the inner 

 margin strongly defined and running obliquely from close to the 

 inner margin of the eye to the hind angle of the prosternum 

 where it meets the outer wall of the sulcus and closes its cavity. 

 T. Adelaides, Blackb., and varipes, Blackb., furnish typical in- 

 stances of the above form of sulcus. The development of the 

 sulci however degenerates by their becoming wider, shallower, 

 and less sharply limited. In some species (e.g. a'pici'penne^ 

 Reitter) the form of the sulci differs from that of the Adelaides 

 group by their inner margin being in its front half nearly parallel 

 to their outer margin and in its hind half (only) running obliquely 

 across to join the outer margin at the hind angle of the pro- 

 sternum. In other species, again (e.g. difficile, Blackb., and 

 lindense, Blackb.), the inner margin of the sulcus reaches the 

 basal margin of the prosternum at a point between the middle of 

 the prosternum and the hind angle of the segment, the hasal 

 margin closing the sulcus by being slightly elevated, and finally 

 there are species (e.g. morio and maurulum, Blackb.) in which 

 the hind margin of the prosternum is not at all elevated, and 

 consequently the hind end of the sulcus is open. 



In my former notices of Trogoderma I have apportioned the 

 species into primary divisions according as the sulci are open or 



