Marvels of the Universe 1059 
of their shells against stones and each other is such that, at least on one occasion, it has caused alarm 
to a portion of the English army. 
The curious may read about this affair in Whistler’s ““ Account of Admiral Penn’s Expedition to 
the West Indies, 1654-5,” and further particulars concerning the habits of the Land Crab may be 
gathered from Patrick Browne’s ‘‘ History of Jamaica.” 
Seeing that they are crabs, it is necessary that, like all other crabs, they should purify their blood 
by means of gills. These are contained in chambers on each side under the upper crust, and in 
the marine species a constant flow of water sets in under the edge of this crust, caused by the in- 
cessant movement of the gills. The oxygen is extracted from this current, which then passes out 
near the jaws. The Land Crab has been so far modified in structure that the gills extract oxygen 
from the air, but they must still be kept moist to ensure their efficient working. To secure the 
Photo by] [E. Step,F.L.S. 
PAINTED GRAPSUS. 
This Crab prefers to climb perpendicular cliffs to running along the shore. It lives in cliff holes. At St. Paul’s Rocks, 
in the Atlantic, Darwin observed it raiding the nests of sea-birds. 
necessary moisture the gill chamber is lined with a spongy membrane which holds a supply of 
water. 
Another. Land Crab is the notorious Robber or Coco-nut Crab, described in early pages of 
this work. 
There are other species that are, so to speak, Land Crabs in the making—crabs that, though 
they live almost entirely above high-water mark, do not venture far from the sea. Such is the 
Beckoning Crab, of the mangrove swamps; such is the Racer Crab, which cannot live in water for 
a single day and collapses after an immersion lasting only for a few hours. Then there is the 
beautifully-marked Grapsus of the Azores, which prefers to climb and run about the perpendicular 
sides of the cliffs, and lives in holes and clefts. Darwin has described how this species, at St. 
Paul’s Rocks in the Atlantic, would raid the nests of the terns, stealing the fish which the parent 
birds had brought for feeding their young. They have even been accused of stealing the young 
birds. _ Prof. Moseley, during the voyage of H.M.S. Challenger, made many observations on these 
crabs, at several places. He says they are more wide-awake than the birds and keep well out of 
reach, so that they are difficult to capture—which the birds are not. 
> 
“NI 
