576 REVISIONAL NOTES ON AUSTRALIAN CARABID^, V., 



what appears to be over-development of characters have 

 always been advanced as an objection to the theory of natural 

 selection ; because, no character could have been carried by 

 natural selection beyond the limit of usefulness or benefit to 

 the species. It has appeared to me, in such cases of hyper- 

 trophy of a character, the reason may have been that it had 

 become, as it were, an essential endowment of the species, and 

 may have kept on gaining in size, when not injurious to the 

 species, by the accumulated force of such endowment. Such 

 a force of endowment could, of course, only operate within 

 bounds limited by natural selection ; as soon as the point of 

 injury to the species was reached it would be checked by natu- 

 ral selection. 



Bringing the scope of our inquiry into resemblances due to 

 convergence within the narrow limits of the Helluonini of the 

 Australian group, we find the following cases which seem to be 

 instances of convergence rather than of reversion. Whether 

 any of them are due to reversionary convergence ; or, whether 

 all of them are merely instances of convergence, unassisted by 

 hereditary influences, are subjects which it is probably not 

 profitable to worry about. In any case, such reversionary 

 influences as may have given them any primary impulse of 

 origination, or direction, are very obscure, and have not been 

 perceived by me. 



(1). A pointed labrum in Pleuracanthus and Hellnonidius 

 (also in Dicranoglossus) . This is more likely to be due to the 

 adoption of the same habits of catching similar prey, having 

 led to analogous development rather than to reversion. 



(2). A furcate ligula in Dicranoglossus and Ametroglossus 

 I see no evidence of any near relationship between these 

 genera, and regard the presence of a forked ligula in each 

 (which is found nowhere else in the tribe) as a case of conver- 

 gence, though these forms may have been derived from a com- 

 mon, remote, ancestral stem in which the ligula was excised. 



(3). The presence of long, pointed lobes to the mentum, and 

 an ordinarily shaped, inner lobe to the maxillae in Helluo and 



