LAND CRABS. 



201 



As we have already pointed out, the branchiae or gills are enclosed between the side walls 

 of the thorax and the over-spreading head-shield (the " Crab-cart " of peasants' children in the 

 English Eastern Counties), and are borne upon the basal joints of the thoracic limbs. As 

 rapidity of movement necessitates increased activity in the circulation of the vital fluid in the 

 body, we thus find that by this simple arrangement the branchiae are brought directly into connection, 

 with the appendages specially engaged in locomotion. In a precisely similar manner we observe 

 that the pectoral muscles in the bird, by their rapid action, accelerate their respiratory functions, 

 consequently those birds whose flight is swiftest, 

 such as the Swallows, naturally breathe most 

 quickly. Amongst the Land and Shore Crabs, such 

 as the Grapsidce, the Ocypodidce, the Gecardnidce, we 

 find some of the most rapidly moving terrestrial forms 

 of Crustacea. Respiration in these Crabs is, however, 

 carried on essentially upon the same plan as in the 

 aquatic species, that is, by means of moistened branchiae 

 or gills, not by pulmonary sacs, as in the Arachnida, 

 nor by tracheae, as in insects proper. Nevertheless, 

 the aeration of the blood in the branchiae of Land Crabs 

 is so much more complete than it is among the aquatic 

 species, that the Land Crabs are easily drowned by 

 continued immersion in water. 



Land Crabs are met with in the tropics in vast 

 numbers. Of these, the most common and best known 

 to us is the Gecarcinus ruricola, or" Countryman Crab," 

 once so abundant in the highlands of Jamaica, and 

 still so formidable in Montserrat and other West Indian 

 sugar-producing Islands (Fig. 17). When the season for 

 spawning arrives vast armies of them set out from the 

 hills, and, undaunted by opposition, march in a direct line 

 towards the sea-shore for the purpose of depositing 

 their eggs. Having reached the destined limit of their 

 joui'ney, they deposit their eggs below high- water mark 

 in the sand, and re-commence their toilsome march to- 

 wards their upland retreats. On their seaward journey 

 they are in full vigour and fine condition, and this is the 

 time when they are caught in great numbers for the 

 table. Their flesh, which is of the purest whiteness, is highly esteemed, but, like that of all 

 Crustaceous animals, is rather difficult of digestion. On returning from the coast they are 

 exhausted, poor, and no longer fit for use. They then retire to their burrows, where they exuviate, 

 or shed their shells, a short time after which operation, and while in their soft state, they are 

 considered by black connoisseurs to be a great delicacy. These Crabs, which take up their abode in 

 the vicinity of sugar-cane fields, are very injurious to the planter, some of the species being 

 particularly fond of the cane, the juice of which they suck and chiefly subsist upon. They also 

 attack and destroy the growing shoots of the young plants. 



Cardisoma carnifex, which usually inhabits the mangrove swamps of the West Indian Islands, 

 lives principally upon the fruit of a species of Annona, which grows in those places. But nothing 

 comes amiss to it. Those individuals whose residence is in the neighbourhood of the cemeteries are 

 said to burrow down to get at the dead bodies, and Dr. Duchassaing tells us that the West Indian 

 burial grounds are pierced in every direction by burrows of these animals. Nevertheless, the 

 Cardisoma is regarded as a luxurious article of food by West Indians, who, however, take care 

 only to eat those which are obtained in the mangrove swamps, as far as possible from the cemeteries. 

 They are caught in box-traps baited with a piece of their favourite fruit, and after their capture 

 they are usually kept some time, and fattened with broken victuals. 

 264 



Fig. 16. MASKED CRAB. MALE. 



(Corystes cassivelaunus.) 



