572 REVISIONAL NOTES ON AUSTRALIAN CARABIDiE, V., 



16(11). Winged; metasternum much longer between middle 

 and posterior coxal cavities than length of posterior 

 coxae, episterna elongate; elytra with ninth inter- 

 stice very narrow in comparison with eighth. 

 17(23). Ligula wide, rounded at apex; elytra with eighth 



interstice pluripuiictate. 

 19(20). Mentum with a short wide median tooth; maxillae 

 with a strong triangular prominence on inner side 



(except in G. longipenne) Gigadema. 



20(19).Mentum edentate ; maxillae with inner side not 



triangularly protuberant in middle. 

 21(22). Prothorax hexagonal, strongly narrowed to base, 

 anterior angles marked in S , rounded in ? , basal 

 angles close to peduncle; <5 with humeral angles of 



elytra rounded Neohelluo, 



22(21). Prothorax transverse, lightly narrowed to base, 

 anterior angles rounded, basal angles distant from 

 peduncle; 6 with humeral angles of elytra dentate. jEnigma. 

 23(17). Ligula furcate; elytra with eighth interstice bise- 



riately punctate Ametroglossus. 



Phylogeny.— In studying the phylogeny of the Helluonini, 

 attention should be given to the "primitive characters" pre 

 viously mentioned, and to those which follow; a careful con- 

 sideration of all of them is necessary in seeking for evidence, on 

 which to base conclusions as to the position of genera in the 

 tribe, or of species in the genera. This part of the subject is 

 treated here only in reference to the Australian Helluonini; and 

 to enable the bearing of some obscure and perplexing phases in 

 the study of phylogeny to be better comprehended the following 

 note on convergence is offered. 



Convergence.- The term convergence has been used by Darwin 

 to denote those resemblances which are so often found between 

 livin^y things, but which are not due to inheritance from a com- 

 mon ancestral type. Few facts in natural history fill the mind 

 with more astonishment than many of the cases of convergence 

 between animals not at all nearly allied. For instance, the 

 resemblance in external form between whales and fish (Origin of 

 Species, sixth ed., Chapter iv., p. 100). 



In the Insecta, there are innumerable instances of convergence 

 between distant members of the class, Wallace gjyes many such 



