CH. XXI.] VARIOUS SPECIES OF CRABS. 283 



counted not fewer than 12,444 eggs beneath the tail, 

 besides others which remained within the body un- 

 protruded. They deposite their eggs in the sand, 

 where they are soon hatched. 



The following account of the remarkable circum- 

 stances connected with a singular trait in the econ- 

 omy of these animals, namely, the periodical cast- 

 ing of the skin, extracted from Dr. Roget's admirable 

 Bridgewater Treatise, will be read with interest. 



" The process by which the periodical casting and 

 renewal of the shell of lobsters are effected has been 

 very satisfactorily investigated by Reaumur. The 

 tendency in the body and in the limbs to expand 

 during growth, is restrained by the limited dimen- 

 sions of the shell, which resist the eiforts to enlarge 

 its diameter. But this force of expansioin goes on 

 increasing, till at length it is productive of much 

 uneasiness to the animal, which is in consequence 

 prompted to make a violent effort to relieve itself; 

 by this means it generally succeeds in bursting the 

 shell ; and then, by dint of repeated struggles, extri- 

 cates its body and its limbs. The lobster first with- 

 draws its claws, and then its feet, as if it were pulling 

 them out of a pair of boots ; the head next throws 

 off its case, together with its antennae, and the two 

 eyes are disengaged from their horny pedicles. In 

 this operation, not only the complex apparatus of 

 the jaws, but even the horny cuticle and teeth of the 

 stomach, are all cast off along with the shell : and, 

 last of all, the tail is extracted. But the whole pro- 

 cess is not accomplished without long-continued ef- 

 forts. Sometimes the legs are lacerated or torn oif 

 in the attempt to withdraw them from the shell, and 

 in the younger Crustacea the operation is not unfre- 

 quently fatal. Even when successfully accomplish- 

 ed, it leaves the animal in a most languid state ; the 

 limbs, being soft and pliant, are scarcely able to drag 

 the body along. They are not, however, left alto- 

 gether without defence. 



