BY T. G. SLOANE. 595 



stem from which G. node is derived, and converged towards a 

 more ancient generalised type by reversionary atavism {antea, 

 p. 57 4). The species of Gigadema may be arranged in four groups, 

 viz., the sulcatum-, grande-, hostocki-, a>nd longipenne-groups ; 

 of these, the two last are most closely related ; the sulcatum-, 

 gr<(nde-, and 6os^oc^i-groups have little relationship to one 

 another, but are bound together by evidence of descent from a 

 common central type. 



Table of Species. 



l(22).Ligula with median depression; inner lobe of niaxillse triangularly 

 protuberant in middle of inner side. 



2(7).Pronotum with the whole upper surface closely punctate. (Palpi 

 short). 



3(4). Elytra with even interstices closely and confusedly punctate... 



G. froggatti Macl. 



4(3). Elytra with even interstices biseriately punctate. 



5(6). Interstices 2-7 convex, nitid in middle; punctures coarse and close 

 together G. sulcatum Macl. 



6(5). Interstices opaque, depressed on apical third, weakly costate towards 

 base, punctures not coarse ..G. hiordinatum '^\. 



7(2).Pronotum with an impunctate central space. (Palpi with penulti- 

 mate joint longer than in Section 2). 



8(15). Labial palpi with apical ji)int at least two-thirds the length of pen- 

 ultimate. (Gula, or cardo of maxilla armed in i ), 



9(10).Prothorax strongly sinuate on sides posteriorly; $ with gula un- 

 armed; cardo of maxilla prominently dentate G. maxillare SI. 



10(9),Prothorax lightly sinuate on sides posteriorly; S with gula armed; 



cardo of maxilla unarmed. 

 11(14). Pronotum with apex truncate, not produced above head; posterior 



trochanters obtuse. 

 12(13). <J .Pronotum with middle part of apex slightly more prominent 

 than anterior angles; process of submentum short, wide, its outer 



angles tuberculiform and pointed outwards G. gulare SI. 



13(12). i .Pronotum with anterior angles more prominent than middle part 

 of apex; process of submentum bifid, the lobes short, triangular, 

 pointed downwards G. rugaticolle Blkb. 



* Note. — It is certain that there is never, in any species, such a variation 

 in the shape of the prothorax, as is indicated by Gestro for G. grande. He 

 has confused the sexes of two different species {postea p. 600). 



