( 314 ) 



Our description and figures, however, will be sufficient, we trust, for recognising 

 the species, and it is to be hoped that, now we have drawn attention to Aiixenia, 

 the peculiar interest attached to all parasites will induce naturalists residing 

 or travelling in the Malayan countries to collect all the stages of development 

 of the insect. 



Since in the earwigs generally the young and adult do not differ very much 

 in structure, especially in the wingless forms, we may assume that also in this 

 case the adult specimens will present essentially the same appearance as the 

 individual here figured (PI. XVI. fig. 1). This assumption, we think, is the 

 more justified as our smaller specimens of Arixeinn differ from the larger ones 

 in a similar way as do young earwigs from adult ones — for instance in having a 

 smaller number of segments in the antenna. 



The large specimens measure 18 mm. from the upper lip to the apex of the 

 pygidium, the small specimens 12 mm. Head, thorax, mouth-parts, antenna, and 

 legs ochraceous; sterna of thorax and the coxae pale buff; abdomen blackish 

 tawny. The whole insect covered with pale ochraceous hairs, which are longest 

 near the edges of the segments. The thoracic nota bear each seven elongate 

 spaces which are devoid of hairs (PI. XVJ. fig. 1). There are no wings. 



Head. 



The head is broader than long, being widest posteriorly. In general outline 

 it agrees with the head of the earwigs, being obtusely heart-shaped. The upper- 

 side slants slightly downwards from near the hindmargiu to the upper lip. In 

 front of the antennae there is a curved depression, which extends from side to side 

 and separates the anterior portion of the capsule of the head, the clypeus, from 

 the central part or frons (= epicranium). The suture situated in this transverse 

 depression is but vestigial. Another suture is found between the eyes ; it is much 

 less distinct than in the earwigs. The occiput (or protocranium), which lies behind 

 this second suture, is divided by a minute central longitudinal suture, as is also 

 the case in the earwigs. The hind portion of the occiput is incurved and centrally 

 depressed, so that the sides are somewhat globose and project backwards. 



The eye is smaller than in the earwigs, and contains only eighty odd facets. 

 It is situated close behind the antenna, and is a little more dorsal than ventral, 

 only a small portion of it being visible in a ventral view of the head (PI. XVII. 

 fig. 1). It is elliptical and but little raised above the surface of the capsule of 

 the head. The somewhat loose arrangement of the facets and their small number 

 indicate that a reduction has taken place, the eye being on the way towards 

 becoming vestigial and lost. 



The antenna is lateral, being inserted where the dorsal and lateral surfaces 

 of the heiul meet. The membrane connecting it with the ca[)snle of the head 

 is rather large, and allows a full j)lay backwards and sideways. The antenna 

 cannot be held straight forward. There are thirteen segments in the antenna of 

 the large sjiecimens. They are nearly circular in a transverse section. The first 

 segment is much longer and thicker than any other, and somewhat curved, as 

 shown in the figure. The second, on the contrary, is very short, and serves as a 

 kind of condylus, the remaining segments forming a flagellum which is freely 

 movable in all directions. The third segment is a little more than one-third 

 the length of the first, while the fourth as well as the fifth are less than half the 

 length of the third, the sixth and seventh being but little longer than the fifth. 



