BY T. G. SLOANK. 577 



G longipenne, seem to me (as argued above) not decided evi- 

 dence of close relationship. This is likely a case of reversion- 

 ary convergence. 



(4). An edentate mentum in DicranogJossiis and JEnigma. 

 Dicranoglossus is far more closely related to HeUuo7iidius, 

 than it it is to JEnigma and Neohelluo, the only other genera 

 without a median tooth to the mentum. However, conver- 

 gence by loss of a character is of far less taxonomic import- 

 ance, and less difficult to explain (such reduction of characters 

 occurs in every direction among insects), than the great deve- 

 lopment of, or acquisition of a character. 



(5). Elytral sculpture in Helluo costatus and the African 

 Tricenogenius. — The resemblance in this case may be due to 

 reversion ; it is a question on which I have not formed an 

 opinion. But the relationship between Helluo and Triceno- 

 genius must be exceedingly remote. 



(6). Colour. — The green colour of HeUuonidius and ^nig- 

 w(i has probably been acquired independently. Chaudoir also 

 reports Pleuracanthus crihricollis as having the elytra of a 

 bluish tint. 



Chcetotaxy. — In the Australian group of the Helluonini, 

 the following hairs are of importance. Head, with one sensitive 

 hair above each eye in all our genera, except Epitnicodema; in 

 all genera of the extra-Australian group there are two hairs. 

 Lahrum : in all the genera of the extra- Australian group 

 there are six sensitive hairs on the labrum, but, in the Aus- 

 tralian group, only Dicranoglossus has more than four sensi- 

 tive hairs (ten) ; in Helluonidius, Helluosoma, and Helluo- 

 dcma there are four hairs ; in the rest of our genera only two 

 fully developed, one near each anterior angle, rising from a 

 conspicuous puncture. Clypeus : HeUuonidius and Dicrano- 

 glossus have two, long, sensitive hairs on each side of the cly- 

 peus, all other genera one hair on each side. Ligula always 

 fringed with setae in the Australian group, and with the usual 

 two, anterior, sensitive setae (in Helluosoma, Ametroglossus, 

 and Dicranoglossus the sensitive setae are unusually distant 



10 



