^PT BY AiTTS. 75 



fig. 5). It is an active bustling little being, and I have 

 kept hundrr ds, I may say thousands, in my nests. They 

 run about m and out among the ants, keeping their an- 

 tennae in a perpetual state of vibration. Another very 

 common species is a white crustacean allied to the wood- 

 louse (PI. V. fig. 7), and enjoying the rather long name 

 of Platyarthrus Hoffmanseggii. Andre only mentions 

 Platyarthrus as living with Formica rufa, Myrmica 

 scabri/nodis, and Leptothorax acervorum. I have 

 found it also with Lasius niger, L. fiavusy and F. 

 fusca. It runs about, and is evidently at home, 

 among the ants. Both Platyarthrus and Beckiay 

 from living constantly in the dark, have become 

 blind ; I say * have become,' because their ancestors 

 no doubt had eyes. In neither of these cases have I 

 ever seen an ant take the slightest notice of either of 

 these insects. One might almost imagine they had 

 the cap of invisibility. 



It is certain that the ants intentionally (if I 

 may so say) sanction the residence of these insects 

 in their nests. An unauthorised interloper would be 

 at once killed. I have, therefore, ventured to suggest 

 that these insects may, perhaps, act as scavengers. 



In other cases the association is more close, and the 

 ants take the greatest care of their guests. 



It appears that many of these insects produce a 

 secretion which serves as food for the ants. This la 

 certainly the case, for instance, with the curious blind 

 beetle, Claviger (PI. V. fig. 8), (so called from its club- 



