320 
hoods on its legs, by the greatly developed spur, and by the great length 
of the proximal tarsal segment in comparison to the tibia. In the other 
species the tibia is at least four times the length of the proximal] tarsal 
segment, while in this species it is only twice as long. 
See Plate I, figures 1, 2, and 3. 1, Megamelus; 2, Leaf-hopper from 
the Juncus area; 3, Leaf-hopper from the area never covered by ordinary 
tides. The species whose hind leg is figured in 2 retreated before the 
tide, but on no occasion during the Summer was the region it inhabited 
completely submerged. These figures show a peculiar development of 
structures of advantage in each particular environment. No. 3 has no 
hoods, No. 2 has them somewhat developed, in No. 1 we find the greatest 
development. If, as I have suggested, these hoods have been developed 
to aid in hopping on the surface of water, No. 8 would have no use for 
them and they would necessarily be useless structures. 
The chief ehemy of the Megamelus marginatus, is the only other perma- 
nent resident of the Spartina area, a small spider, Grammonata trivittata. 
Its principal source of food is this leaf-hopper. 
The hoods on its feet, the greatly developed proximal tarsal segment, 
and the spur, are the peculiar modifications which determined that this 
leaf-hopper should inhabit this particular region. But why it is only 
found in the Spartina region, is not as easily answered. It may have been 
the severer competition in the other regions of the marsh, or perhaps the 
Spartina grass is its favorite food, the one on which it is especially” 
adapted to live; or, again, the habits necessary for its continued existence 
in the tidal zone may make it the easy prey of its natural enemies living in 
the other areas. 
I could not compare the resistivity of this leaf-hopper to drowning 
with that of those farther back on the marsh, because I could not get 
any of them to remain under water without placing them in vials covered 
with cheesecloth. Two to four hours submergence usually killed them. 
Even the leaf-hopper of the Spartina could only survive for several hours 
when submerged in this manner. This may suggest that the leaf-hopper 
may secure its air supply from the Spartina by piercing the blade to the 
air channels. I have no experimental evidence to prove this. 
GRAMMONATA TRIVITTATA. 
This spider inhabits the salt marshes from Long Island to Maine 
Emerton). The females are about 3.5 mm. jong. Their color is a dark 
t=) 
