OR, PLAIN 



TEACHING. 



processes, and having large 

 sessile eyes, 7 ; in the second 

 stage it presents more of the 

 crab-like character, the abdo- 

 minal organs being more fully 

 developed, 8. A similar metamor- 

 phosis takes place amongst both 

 the highest classes of Crustacea ; 

 and in their earlier stages of 

 development they very nearly 

 resemble each other, though they 

 may differ very widely when 

 fully developed. 



The periodical visitations of land crabs to the 

 sea, is one of the most curious facts of natural 

 history. When the season for spawning arrives, 

 they set out for the hills in a direct line, and 

 march in vast companies to the sea shore. On 

 this grand expedition nothing; is allowed to turn 

 them from their course. With unyielding per- 

 severance they surmount every obstacle which 

 may intervene, whether a house, rock, or other 

 body, not avoiding the labour of climbing by 

 going round, but ascending and passing over it 

 in a straight line. Having reached the destined 

 limit of their journey, they deposit their eggs in 

 the sand, and recommence their toilsome march 

 towards their upland retreats. They set out after 

 nightfall, and steadily advance, until the ap- 

 proach of daylight warns them to seek con- 

 cealment in the inequalities of the ground, or 

 among any kind of rubbish, where they lie 

 ensconced until the stars again invite them to 

 pursue their undeviating course. 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. Re- 

 turning from the coast, they are exhausted, 

 poor, and no longer fit for use. They then 

 retire to their burrows, where they slough or 

 shed their shells ; a short time after which 

 operation, and while in their soft state, they are 

 considered by epicures as most delicious, and 

 are consequently sought for with avidity.* 



The lobster, 9, is a description 

 of long-tailed crab. They are 

 exceedingly active in the water ; 

 they can run nimbly, and if 

 alarmed can spring from a con- 

 siderable distance, forwards or 

 backwards. Like crabs they 

 shed their coverings at parti- 

 cular seasons, and this process is 

 one of a very remarkable nature. 



* Maunder'* Treasury or' Natural History 



In the lobster, the process of shell casting 

 appears to differ in some peculiar respects from 

 the like process in the river cray-fish. The 

 lobster to the last is ravenous and vigorous, and 

 instances have been known in which, enticed by 

 the bait, lobsters about to cast their slough 

 have entered into the fishermen's treels or traps, 

 and on the men commencing to handle their 

 prize, the animal has slipped away, leaving its 

 empty husk in the grasp of the astonished 

 fisherman. "It was by a circumstance some- 

 what similar," says Mr. Couch, "that the op. 

 portuniry is afforded me of giving a minute 

 description of a very perfect case, left by the 

 creature when it made its escape, for escape it 

 did, to the no small annoyance of the fisherman, 

 who had calculated on the possession of a prize 

 of somewhat above the ordinary magnitude. I 

 cannot find that any extraordinary actions or 

 contortions have been observed in the lobster 

 when engaged in delivering itself from its 

 trammels, or that the time is prolonged, as in 

 the case of the cray-fish ; and it is certain that 

 when freed it possesses great activity in effecting 

 its escape. In the specimen referred to. the 

 cases of the antenna and palpi were perfect to 



9 



their minutest extremities ; the stalk also, and 

 the transparent covering of the eyes, were 

 uninjured ; the segments and joints of the 

 posterior part of the body, with the caudal 

 plates, were all joined together, but without any 

 intervening membrane ; and the inferior parts 

 from be neath the snout, including the jaws, the 

 jaw-feet, the chelae and legs, with the sternal 

 (breast) plate, oesophagus, and internal coat of 

 the stomach, formed one connected portion, w hh 

 no further separation than arose from the 

 absence of every portion of membrane." The 

 manner in which the animal escaped was not to 

 be mistaken. "Through the middle of the 

 carapace ran a line as straight as if it had 

 been cut with a knife, and evidently formed by 

 a natural process of separation, for it even 

 proceeded through the centre of the snout, to 

 the terminal pointed process at the root which 

 turned off to the right side, so that the least 

 effort by the animal was sufficient to afford it a 

 passage." 



