4o8 



in jacohsoni than in csau, and the labium proper and the palpi 

 correspondingly longer, as in the case of the clipeus and labrum 

 on the upperside of the head. The hind margin of the mentum 

 is somewhat angulate in the centre in jacohsoni. The apical 

 segment of the labial palpus, in contradistinction to esau, bears 

 on the inner surface a number of strong, sharply pointed, spine- 

 like bristles, which are curved proximad, not being directed 

 distad like the ordinary slender bristles which are placed on 

 the lateral and outer surfaces (text-fig. 22, Ip). The ligula 

 (li) is divided down to the mentum much as in esau, but its apical 

 segment is rather longer than in that species. Above the ligula 

 there is a membranous cone which forms the lower wall of the 

 mouth. The upperside of this cone is divided into three small 

 lobes of nearly equal length, the hypopharynx or endolabium, 

 the lateral lobes partly covering the median one, as figured 

 by Jordan (1909). In esau these lateral lobes slightly curve 

 sideways, whereas in jacohsoni they are more symmetrically 

 rounded. 



Thorax. 



The thorax of Arixenia is of the same type as in wingless 

 Earwigs. The notai plates, however, are more independent, and 

 less closely imbricated together. In esau the three tergites are 

 slightly convex with the lateral margins rounded and feebly 

 widened out, the pro- andmesonota being also rounded posteriorly. 

 In jacohsoni the pronotum is distinctly truncate and therefore 

 does not exceed the mesonotum so much in length as in A. esau. 

 Moreover, all three nota have broadly explánate margins in 

 jacohsoni, especially the pro- and mesonotum. These margins 

 are distinctly curved upwards, being broader in the than in 

 the ¿. The mesal line is strongly impressed on the pronotum, 

 less so on the other two nota. It is curious to note that the 

 differences between the uppersides of the two species are reversed 

 on the underside. The sterna are narrower in jacohsoni than 

 in esau, and the pro- and mesosterna are posteriorly narrowed 

 and rounded, not being truncate as in esau. The short and 

 broad sternal plates somewhat resemble those of certain rather 

 peculiar apterous Protodermaptera, e.g. Karschiellinœ and 

 Parisolahinœ. 



