VI INTRODUCTION. 



markings ; another was black, with two bright ultramarine spots in the middle of the 

 carapace; while another species was grey, marbled with white, with an enormous light 

 yellow chela. These Gelasimi cover the ground by thousands, stalking about in a deliberate 

 manner, and holding up and occasionally snapping the claws of their huge fore-legs. 

 Notwithstanding that they appear to be over-burdened with this unwieldy member, they are 

 by no means easy to capture, but run quickly to the mouths of their burrows, where they 

 remain stationary, holding up their fore-claws as organs of defence, and, if further pursued, 

 retreat backwards into their holes, their bodies protected by the same member. In the 

 pools of fresh water and under damp stones, a dark olive-green Sesarma with bright yellow 

 blotches was obtained, and on the coast numbers of the elegant and agile Thelphusa grap- 

 soides, which is found on the coral flats left dry by the receding tide. The Cliasmagnathus 

 convexus of De Haan is another crab which appears to be rather common among the 

 Philippine Islands. I have found it in the company of Xenophthahmis pinnotherides, in the 

 firm black mud of Manila Bay, where it forms oblique cylindrical holes. 



Near the Dyak village of Samahrtan, not far from the mouth of the Lundu River in 

 Borneo, there are certain mud-banks left dry at low-water, and which are perfectly cribriform 

 with the cylindric holes of Gelasimi, Ocgpode, and other genera. When their communities 

 are no longer flooded by the water, these Crustaceans make their appearance in large 

 numbers, but retreat on the slightest alarm into their subterranean burrows. They are of 

 every variety of colour, some of them being milk-white, some purple, others reddish and 

 mottled, while many are perfectly black. So numerous are these crabs, that seen at a little 

 distance they give the surface a variegated appearance, nearly obscuring the original colour 

 of the mud. 



In many parts of Borneo, as soon as the water recedes from the shore on the ebbing of 

 the tide, and the large firm mud-flats are left exposed, numbers of Crustaceans of different 

 genera and species issue from their various holes and hiding-places. The males of many 

 species, after looking cautiously around them, stalk a few paces with their huge fore-legs 

 raised, the claws of which they snap frequently together, producing a slight clicking sound, 

 then rushing eagerly towards the females they embrace them with their fore-legs. The 

 salute is very brief, and is immediately followed by the swift retreat of the females into their 

 different burrows. Other species are seen feeding on worms and shell-fish, feeding alternately 

 first with one hand and then with the other. The common species of Grapsus varius is 



