MARINE MISCELLANEA. 239 
entering the tropics, the large Mangrove Crab, Scylla serrata, almost equal in 
dimensions to the British “ Parton,” becomes fairly plentiful, and is held in high esteem. 
As its popular name implies, the favourite haunt of this crab is the dense mangrove 
thickets, wherein it excavates deep burrows, from which the experienced fisherman is 
wont to dislodge it with a long hooked wire. 
Apart from the economical varieties, Australian waters produce an infinity of bizarre 
Crustacean types. Not the least notable among these are the relatively small mangrove- 
frequenting crabs belonging to the genus Gelasimus. As many as seven species have been 
recorded as inhabiting Australia. They all share the same eminently gregarious habits, 
forming regular warrens with their associated burrows on the sea-shore, or more commonly 
among the mangroves. The special structural distinction of the members of this genus 
is the huge relative size of one of the larger fore-claws, or “cheele,” of the male 
individual. Sometimes it is the right and sometimes the left claw which exhibits this 
abnormal development; though, as shown in the photographs of one of the most con- 
spicuous North Australian species, reproduced on the following page, in as many as 
five out of six of the crabs figured, this larger chela is the left one. The particular 
species, Gelasimus coarctata, here portrayed, is remarkable for its brilliant colouring, 
as well as for its grotesque shape. Except the back of the carapace, which is 
glossy black, the huge claw, the under surface, and all the other limbs are a most 
brilliant scarlet vermilion, inclining to crimson. The aspect, in fact, of a number 
of these crabs seen from a little distance, as they lie stationary at the mouths 
of their burrows, against the dark background of mud and mangrove, is that of hot, 
glowing coals. Presently one of these living coals will move out towards another one. 
It is the literal carrying of a firebrand into the enemy’s camp. The two presently become 
engaged in a deadly combat, there is a rapid retreat of the vanquished warrior, and 
he disappears into his hole like an extinguished spark. Advance a step nearer, and 
the whole community as suddenly and simultaneously vanish, leaving the spectator in 
possession of the seemingly utterly barren and untenanted mud-flat. If he stands still for 
a brief interval, they one by one re-appear at the mouths of their burrows and illumine 
the landscape with their glowing tints. In the third figure, from the top of the group 
here portrayed, a male crab of this species is represented very nearly the natural size. 
The female is somewhat smaller, and possesses two very tiny pincers, as homologues 
of the large and little claw of the male. Two examples of this relatively unarmed sex 
may be readily identified in the lower portion of the accompanying illustration, one 
of them occupying a position immediately above the two champions fighting in the left- 
