APTERA 



195 



congregate in masses on the surface of the rock pools. This 

 Amirida Can endure prolonged immersion; but both the ob- 

 servers we are quoting say that it is, when submerged, usually 

 completely covered with a coat 

 of air so that the water does not 

 touch it. The little creature 

 can, however, it would appear, 

 subsist for some time in the 

 pools of salt water, even when 

 it is not surrounded by its 

 customary protecting envelope 

 of the more congenial element. 

 Its food is said, on very slender 

 evidence, to consist of the re- 

 mains of small marine animals, 

 such as Molluscs. We repro- 

 duce some of Laboulbene's 



Fig. 100. — Amtrida maritima : A, imder- 

 surlace ; a, papilla of ventral tube ; B, 

 prostemmatic organ of young ; C, of 

 adult. ( After Laboulbene. ) 



figiu-es (Fig. 100) ; the under-surface shows at a the divided pap- 

 illa of the ventral tube ; B, C represent the peculiar prostemmatic 

 organ, alluded to on p. 193, in its mature and immature states. 



Very little information exists as to the life-history of the 

 Aptera ; as for their food, it is generally considered to consist of 

 refuse vegetable or animal matter. It is usual to say that they 

 are completely destitute of metamorphosis, but Tenipleton says of 

 Zepisma niveo-fasciata that " the young differ so much from the 

 mature Insect that I took them at first for a distinct species ; the 

 thoracic plates are proportionately less broad, and the first is 

 devoid of the white marginal band." As regards the moults, it 

 would appear that in this, as in so many other points, great 

 diversity prevails, Grassi stating that in Campodea there is a 

 single fragmentary casting of the skin ; and Sommer informing us 

 that in Mmrotoma plumhea the moults are not only numerous, 

 biit continue, after the creature has attained its full growth, 

 throughout life. 



A very marked feature of the Aptera is their intolerance of a 

 dry atmosphere. Although Campodea can exist under very 

 diverse conditions, it dies very soon after being placed in a dry 

 closed tube ; and the same susceptibility appears to be shared by 

 all the other members of the Order, though it is not so extreme 

 in all ; possibly it may be due to some peculiarity in the structure 



