332 



been submerged by the tide. They had migrated to the outer Spartina 

 areas during the low tide period. They are very abundant in the higher 

 marsh areas. 



It would be extremely interesting to know something of the life his- 

 tories of the insects of the between tides zone, especially as to where 

 they spend the winter, as to the methods of egg laying, and as to the 

 types of larvae. 



Conclusion. 



In almost every insect of the between tides zone there appears to 

 be some peculiar protective feature ; as, unique instincts, especially 

 adapted external parts, or a greater resistivity to drowning. 



Unique instincts, to prevent themselves from being washed away by 

 the tides, are well shown in the tenacious clinging to the blades of Spar- 

 tina by the Grammonata trivittata. Megamelus marginatus, and Clubonia 

 sp ( ?) . Another feature of the same type is the crawling of the Bembidium 

 constructum under the gravel. That the environment has undoubtedly led 

 to the formation of these instincts is illustrated by the comparison of the 

 habits, when submerged, of the spiders of the Spartina area with those 

 found higher on the marsh. Another instinct which serves the same pur- 

 pose is the venturing forth for food by the Salda only ou sunny days at 

 low tide. The Grammonata trivittata and Megamelus marginatus un- 

 doubtedly rest head downward on the Spartina grass to prevent themselves 

 from being caught unawares by the rising tide. 



Inconspicuousness as a means of protection from aquatic enemies is 

 shown by the swimming of the Salda to the Fucus thallus when disturbed 

 during high tide. Other reactions serving the same purpose, are illus- 

 trated by the resemblance of Megamelus to the Spartina blade, the crawl- 

 ing the Grammonata into the pits at the junction of blade and stem, and 

 the living of the beetles in burrows. 



That one of the factors which determines the surviving species in a 

 between tides zone is an ability to resist drowning, is shown by a com- 

 parison of the resistivity of Grammonata and Clubonia with that of other 

 spiders. 



A modification of the external features as an adaptation, is shown in 

 the greatly modified legs of the Megamelus marginatus and in the short, 

 stiff hair of the Grammonata trivittata. The legs of Lycosa communis 

 are not essentiallv different from tliose of other Lycosa 3 ; yet tbeir long. 



