ANALOGOUS TYPES. 107 



between those mentioned above, on account of 

 the large shield of the Turtle. But there are 

 Turtles with a soft covering, and there are some 

 Toads with a hard shield over the head and neck 

 at least, and both groups are alike distinguished 

 by the shortness and breadth of the body and 

 by the greater development of the limbs as com- 

 pared with the lower Reptiles. But here again 

 there is the same essential difference in the mode 

 of development of their young as distinguishes 

 all the rest. The two series may thus be con- 

 trasted : — 



Such corresponding groups or parallel types, 

 united only by external resemblance, and dis- 

 tinguished from each other by essential elements 

 of structure, exist among all animals, though 

 they are less striking among Birds on account 

 of the uniformity of that class. Yet even there 

 we may trace such analogies, — as between the 

 Palmate or Aquatic Birds, for instance, and the 

 Birds of Prey, or between the Frigate Bird and 

 the Kites. Among Fishes such analogies are 

 very common, often suggesting a comparison 

 even with land animals, though on account of 

 the scales and spines of the former the likeness 



