( •■'13 ) 



DESCRIPTION OF A NEAV KIND OF APTEROUS EARWIG, 

 APPARENTLY PARASITIC ON A BAT. 



By K. JORDAN, Ph.D. 



(Plates XVI., XVII., XVIII.) 



HE insect which forms the subject of the present paper was discovered by 



T 



Messrs. Ed. Gerrard & Sous, of Oamdeii Town, " in the sack formed by 

 the membrane of the wings of Cheiromeles torquatus," the naked bat of the Sunda 

 Islands. The bat has an exceedingly strong and nauseous smell, and is known 

 from the Malay Peninsula, Rnmatra, .Java, and Borneo. It flies at dusk, and 

 sleeps in daytime in hollow trees and in fissures of the soil and rocks. Both sexes 

 of the bat have a large gular poneh, which is said to be used for storing the 

 young during flight — Mr. Gerrard informs me that one of the bats in his possession 

 had a young one in the pouch — and it is suggested tliat, in the case of twins being 

 born, the father and mother take each charge of one of the offspring. Besides 

 the excretions of the gular glands there may occur at times an accumulation of 

 the excrements of the young bat sufficient for insects to feed and thrive upon. 

 Messrs. Gerrard received a number of specimens of Cheiromeles torquatus from 

 Sarawak, where they were obtained by Mr. Chas. Hose. In the pouch of one 

 of these specimens the new insect was found, which we name 



Arixenia esau gen. et spec. nov. 



At first sight we were inclined to attribute to accident the occurrence of such 

 a large insect in the nursing-pouch of the naked bat. But the study of 

 Arixenia has convinced us that the insect, which is related to the earwigs, is 

 parasitic. Indeed, it does not require a great stretch of imagination to under- 

 stand how a kind of earwig arrived at living in the pouch of a creature sleeping 

 in fissures of rock or soil. The reduction of the eye and the structure of the 

 mandible and of the inner lobe of the maxilla seem to indicate that Arixenia 

 lives in a dark place, and feeds principally on matter which has already been 

 masticated or requires little mastication. The contents of the alimentary canal 

 consist of a soft amorphous matter and numerous fragments of insects. We 

 obtained from the anterior jjortiua of the oesophagus, within the head, two 

 comparatively large pieces of chitiu, which proved to be the apex of the tibia 

 and the first and the base of the second tarsal segment of, we think, some small 

 fly. The fragments have the appearance of being fresh, and we believe we detect 

 some remnants of muscles attached to them, which, if correct, would justify the 

 conclusion that Arixenia feeds, perhaps incidentally, also on live or freshly killed 

 insects. 



Arixenia is interesting not only on account of the peculiar place where it 

 was discovered, but also for the morphological and anatomical characteristics 

 which it presents. We received four specimens, two of them being half as large 

 again as the other two. They were in alcohol, and very well preserved as regards 

 the chitinous jiarts. But the soft inner organs are so much macerated that we 

 cannot give any histological details. Moreover, none of the specimens are quite 

 full grown, so that the account of the anatomy is incomplete also for this reason. 



