4 ARKIV FÖR ZOOLOGI. BAND 10. NIO f). 



club is apparent: the four (to five) last joints are more or less 

 grown together, the penultimate joint being a little excavated 

 at the apex and receiving the last one. (Cnfr. Paussoceros M.) 



In West\vood's description of E. Pascoei we only get 

 the information: »Antennarum clava oblongo-ovali, depressa, 

 disco supero et infero transverse triimpresso, marginibus 

 paullo undulatis et breviter spinulosis.» But from the figure 

 (Pl. 3, Fig. 3) it is evident that the »club» consists of at 

 least four joints, the fourth one verv likely receiving the 

 small reduced top-joint, as is actually the case with the new 

 genus Paussoceros M. and partly with the new species de- 

 scribed below, although here the top-joint is less reduced. 



In the genus Mesectrephes M. the reduction has gone still 

 further, all the proximal joints having grown finely together, 

 forming a real, broad club, but still showing traces of the 

 different joints in the shape of impressions on the posterior 

 margin. 



The extreme limit of reduction is, however, exhibited by 

 the genus Monectrephes M. with only three joints, the last 

 one being very long and forming a solid club. No traces of 

 any separating sutures can here be seen. 



Apparently the second joint is the first to be subject 

 to reduction. In the genera Paussoptinus and Leaptinus it 

 is practically rudimentary, being visible only from underneath. 

 In the allied genus Paussoceros tlie second joint in number 

 very likely is the true third. 



It is of interest to note that also among certain Paus- 

 sidce a similar reduction in the proximal part of the antennse 

 takes place. Of about 300 species hitherto described only 

 four, the Asiatic Protopaussus fece Gestro, P. Walkeri Waterh., 

 the Javanean P. java7ius Silv. and the Australian Megalo- 

 paussus amplipenyiis L. have 11-jointed antennae. In 31 egalo- 

 paussuSy however, the second joint is extremely small and 

 visible only from underneath. 



That a reduction probably also takes place with the 

 middle joints is shown by the genus Polyplocotes with its nine 

 joints. Ex analogia it is permissible to draw the conclusion 

 that the enlarged eighth joint here is homologous to the tenth 

 characteristically enlarged one in Diplocotes or the ninth in 

 Decemplocotes. 



