24 



at high tide, this is by no means always the case. Some of the most intelligent 

 of all the crabs are of amphibious habit. 



Most of the Imid-crahs also belong to the Gaiomeiopa, though a few species 

 of Telphuddai are terrene. They prefer damp jungle, where they either burrow 

 in the earth or crouch under roots and fallen timber. Though their gills are 

 well developed, they also in part respire by means of the thickened linmg- 

 membrane of their greatly-enlarged branchial chambers ; but it is essential that 

 the air should be moist. Though they are typical inhabitants of the moist 

 jungles of the islanda and seaboard, yet they are also found at elevations of 

 several thousand feet in places where the rainfall is heavy. 



Of the deep-sea crah.-i, those that live at moderate depths, to which it is 

 possible that a certain amount of light penetrates, very often have the eyes 

 enlarged; while those that live in the uuilluminated abysses very commonly 

 have the eyes small and deficient in pigment. 



Although no existing members of the Arthropod phylum exceed the largest 

 Brachyura in size, yet the size of the body in this suborder is extremely variable. 

 At "the one extreme we find GoUodes malabaricus, an inhabitant of these seas, of 

 which the carapace, in an adult and egg-laden female, is less than one-sixth of 

 an inch in its greatest diameter, and Ehalia diadmnena, another inhabitant of 

 these seas, the greatest diameter of the carapace of an egg-laden female of which 

 is less than one-fifth of an inch : at the other extreme we have the Australian 

 Pseiulocarcinus gicjas whose carapace is said to reach a breadth of about two feet, 

 and the Japanese Kaempferia (Macrochira) Kaempferi the span of whose cheli- 

 peds attains to ten feet. 



The Brachyura as a whole are the most highly organized and most intellig- 

 ent of the Crustacean" class. The Cyclometopes and Catometopes are particu- 

 larly alert and active, and among several of the gregarious species of amphibious 

 Catometopes life appeal's to be almost as complex as it is among many insects. 



Although parental care does not go beyond the simple and almost mechanic- 

 al stage of carrying the eggs until they are hatched, yet in some Brachyura the 

 sexual feelings are sufficiently sustained and complex to give rise to well marked 

 " secondary " differences between the sexes and between the adults and immature 

 young of the male sex. 



If the males are not larger than the females, yet, at any rate, it is very 

 common to find the male having one or both of its chelipeds very much larger 

 than those of the female, the difference in size being usually most marked in the 

 chelse. We know that in some cases the males use their enlarged chelipeds for 

 fighting with each other. On the other hand, it must be remembered that there 

 are many species of crabs in which the chelipeds show no sexual differences 

 whatever. 



