3 22 4 THE JOINTED ANIMALS 



flattened into a paddle. Connecting the present with the following section, is the 

 family Thelphusida ', which contains a number of genera and species found in fresh- 

 water streams, or on land, and sometimes ascending mountains, in temperate and 

 tropical regions. One of the best-known species is the South European Thelphusa 

 fluviatilis, which swarms on the muddy banks of the Lake of Albano, and is also 

 abundant in the neighborhood of Rome, where it is captured for sale. Another 

 well-known form is the Indian land crab (T. indica], to which the species here 

 figured is nearly allied. 



The second tribe (Catometopa) is characterized by the broad and squared 

 frontal region of the carapace being bent downward. It is typically represented 

 by the family Gecarcinidce , including most of the true land crabs. A large number 

 of these belong to the genus Gecarcinus, which has representatives in both the 



INDIAN LAND CRAB. 

 (Four-fifths natural size. ) 



Eastern and Western Hemispheres. Two inhabit the West Indian islands, and of 

 one of these (G. ruricola) from Jamaica a full account has been given by 

 Mr. Browne. 



These crabs are generally found at a distance of from two to three miles from 

 the sea, where they spend the day under stones, or in other sheltered situations. 

 Pairing takes place in the spring; and shortly afterward the whole population 

 makes a move for the sea, in which the females lay their eggs. When seized with 

 this migratory instinct, nothing can turn them from their course. Issuing from 

 hollow trees, from under rocks, and out of innumerable holes, they muster in a host 

 so fast that they thickly cover an area more than a mile long, and upward of forty 

 yards wide. The males lead the way, and the band proceeds in a straight line to 

 its destination, climbing over every thing that comes in its road, be it hedges, houses, 

 churches, hills, or cliffs, and rather clamber up at the peril of their lives than make 



