374 LETTER LVIII. 



main for some minutes to let the waves pass over 

 their shells. After this they leave the margin of the 

 ocean, in search of some retired situation on land, 

 where they remain a few days, and again return to 

 the sea shore, where they deposit their spawn, the 

 greatest part of which is devoured by different fish, 

 while the eggs that escape are hatched under the 

 sand. 



The strength of the old ones being by this time al- 

 most exhausted, they make holes in the ground, in 

 which they hide themselves while they cast their 

 shells, remaining for five or six days in a state of tor- 

 pidity i During that period they grow very fat, and 

 are then in the highest perfection. In some countries 

 the slaves are entirely fed with them; and by many 

 people they are considered as delicious food. The 

 whole time of performing their expedition, from the 

 moment of their outset to that of their return to their 

 inland retreats, is sometimes not more than six or se- 

 ven weeks; but when great obstacles impede their 

 march, it often requires more than three months. 



CRUST ACEOUS FISHES OF THE TORTOISE KIND, 



form also a curious subject of natural history. Ani- 

 mals of this nature are divided into two classes, one 

 residing on land and the other in the water; and in 

 this respect they resemble the crab genus. The two 

 species are distinguished by the names of the tortois-e 

 and the turtle, the former being an inhabitant of the 

 land, and the other of the sea. In their internal con- 

 formation they bear a strong resemblance to each 

 other, but they differ very much in size. 



The land tortoise is found from one to four or five 

 feet in length, and from five to eighteen inches across 

 the back. The head, which it can, at pleasure, pro- 

 tend beyond, or draw within the shell, resembles that 

 of the serpent kind, The. tail is long and scaly? and 

 the exterior covering of the animal is composed of se- 

 veral pieces of shell joined together in the firmest 

 m st compact manner, and somewhat resembling* 



the tiling of a house. 



This animal., which isiof the ntost pacific disposir 



