Tortoises.

Tortoises are broadly divided into three species, namely, land tortoises; fresh water tortoises, of which there are no less than forty-six varieties; and marine tortoises, well known to the citizens of London, in the shape of turtle-soup.  The land tortoises subsist on vegetables, and are said to live occasionally more than two hundred years.  The two first cases devoted to Testudinata (18, 19) contain the American, Indian, and African varieties of the land tortoise.  Here is the gigantic tortoise from Galapagos, for the flesh of which many a sailor has been grateful.  The visitor will remark that the shells of some of the sub-families are handsomely marked.  The fresh water tortoises, having the greatest number of sub-families, occupy three cases (20-22).  This species is found in the marshes or rivers of warm climates, where they prey upon small fishes and frogs.  The thurgi tortoise of India, and the American snapping-tortoise, grow to a great size.  In the lower part of case 22 are specimens of those tortoises which sleep with their heads bent under the margin of their shell.  In the last case devoted to tortoises, are those hard tortoises known as the three-clawed terrapins of Asia, Africa, and America.  These are the strictly carnivorous family that feed in the water; and may be seen preying upon the human remains that float down the Ganges.  Under these terrible epicures are the marine tortoises or turtles; and among them the green turtle of the tropics.  Shellfish and sea-weed are its chief food; of its flesh, all Londoners who have not tasted it, can speak pretty confidently from hearsay.  It grows occasionally to a great size; those smaller ones which the citizens prize weighing generally about 600 lb.  Here too are the turtle of the Mediterranean, and the hawksbill turtle of Arabia, to which ladies are indebted for the choicest of their tortoise-shell combs.  Having sufficiently dwelt upon the interesting histories of the tortoises, the visitor’s way lies forward in the direction of the two cases next in order of succession, which are devoted to the Loricata, or

Crocodiles.

The varieties of this family are not many; they are grouped in three cases (24-26).  Here are the terrible common crocodiles which have long been the terror of the people whose native land they inhabit; the alligators, which patronise America exclusively; and the gavials of India.  They are said to act as orderlies, in the rivers they frequent, devouring all the putrid matter that would else infect the atmosphere.  Here too are those curious snakes which are equally thick at either end—­a peculiarity which has earned for them the appellation of double-headed, and the supposed power of walking indifferently forwards or backwards.  The visitor now approaches the

Frogs,