AKURIDA. 359 



The habits of Anurida have been observed by the 

 present writer principally on the shores of Port Erin Bay 

 in the Isle of Man.* Abont the rock-pools in that locality, 

 when the tide is low and the weather calm and bright, 

 numbers of this insect are generally to be seen. It may 

 be found both on the surface of the water and on the 

 surrounding rocks and weed. Anurida, unlike the 

 majority of the Collembola, is unable to perform any 

 leaping movements on account of the atrophy of the 

 springing-organ, and it is only capable of a moderately 

 active crawling motion. Those individuals which are to 

 be seen floating on the rock-pools are only able to walk 

 over the surface-film while the water remains motionless. 

 When, however, the slightest ripple arises they become 

 drifted about from one part to another in a helpless con- 

 dition until they are enabled by chance to cling to the 

 sides of the pools and crawl out on to the surrounding 

 rocks and weeds. Frequently numbers get blown together 

 into little groups on the surface of the water, and the 

 individuals composing them may be seen actively crawling 

 over one another and apparently endeavouring to reach 

 the shore. Sometimes these groups are of a considerable 

 size and may consist of a hundred, or more, individuals. 

 There is every reason to believe that their occurrence on 

 the surface of the water is not due to the insect voluntarily 

 resorting to that medium, but that it is merely the result 

 of accident. Numbers of the insect frequently fall into 

 the pools in their attempts to climb steep rock surfaces, 

 and also very many get blown thither by gusts of wind. 



When the weather is cold and stormy, or otherwise 

 unfavourable, very few Anurida are to be found, and 

 often they appear to be absent altogether. At these times 



* On the Continent the habits of the insect have been studied to 

 some extent in France by Laboulbene (2) and Moniez (4). 



