382 



VERTEBRATA. 



THE IGUAXODOX. 



which bear the different colors ; these are more or less extended, according to the quantity of 

 blood that roaches them, and the change of color is thus effected. 



There can be little doubt that this is a provision to enable this sluggish animal to approach its 

 prev. "The more we search into the habits and peculiarities of animals," says an eloquent 

 writer, "the more arc we led to admire the wisdom and goodness of the Creator. Throughout 

 the animal creation, the adaptation of the color of the creature to its mode of living and place 

 of concealment, is highly remarkable, considered in reference to its preservation. If we look 

 around, we shall discover that the colors of the smaller animals, and a nmltitude of insects, con- 

 tribute materially to their safety. Caterpillars which feed on leaves are generally either green, 

 or have a large proportion of tliat hue in the colors of their coats. So long as it remains still, 

 how diffirnlt it is to distinguish the grasshopper from the leaf or spray on which it rests! The 

 butterflies that flit among the flowers are decked in varied hues like them. The little birds that 

 haunt the hedge-row side have feathers on their backs which harmonize with the color of the 

 leaves, and feathers on their breasts which borrow the white hue of heaven ; these render them 

 less visible to the hawk above, or to the prowling cat beneath. The wanderer in the fields almost 

 treads upon the skylark before it rises, warbling merrily to Heaven's gate. The partridge can 

 hardly be distinguished from the stubble amongst which it makes its nest ; and it is considered 

 an accomplishment for the sportsman to be able to find the hare sitting. In northern countries, 

 the winter dress of the hare and the ptarmigan is white like the snow. 



" If we turn to the waters, we shall find that it is nearly the same Avith its inhabitants. Frogs 

 vary their color according to the nature of the mud or sand at the bottom of the ponds or streams 

 they frequent ; nay, the tree-frog, Hyla viridis, takes its name from the color which is so difficult 

 to see among the leaves, where it adheres by the cupping-glass-like process at the end of its toes. 

 The fish, especially those which inhabit fresh-water streams, are distinguished by the same pecu- 

 liarities. Their backs are comparatively dark, like the water above them, and it requires some 

 practice to discover them as they glide along the bottom of the clear brook in thick dusky shoals. 

 Tliey come like shadows and so depart, under the gaze of the spectator. It is diflicult to dis- 

 tinguish the pike — "the ravenous luce," as old Izaak Walton calls it — with its dark-green mottled 

 back and sides, from the similarly-tinted leaves amid which that fresh-water shark lies on the 



