196 FACTS AND FANCIES. 



able contrivance was temporary, and probably 

 adapted to some peculiarities of the habits and 

 food of these animals occurring only in the 

 geological period in which they existed. 



Examples of this sort of adjustment are found 

 in other types of animal life. In the beautiful 

 Portuguese man-of-war (PhyscUia) and its allies 

 flotation is provided for by membranous or car- 

 tilaginous sacs or vesicles filled with air, and 

 which are the common support of numerous 

 individuals which hang from them (see Fig. 1 8) . 

 In some allied creatures the buoyancy required 

 is secured by little vesicles filled with oil se- 

 creted by the animals themselves. 



In each of these cases we have a skilful adap- 

 tation of means to ends. The float is so con- 

 structed as to avail itself of the properties of 

 gases and liquids, and the apparatus is framed 

 on the most scientific principles and in the most 

 artistic manner. That this apparatus grows and 

 is not mechanically put together, and that in 

 each case the instincts and the habits of the 

 animal have been correlated with it, can scarce- 

 ly be held by the most obtuse intellect to in- 

 validate the evidence of intelligent design. 



3. Structures apparently the most simple, and 

 often heedlessly spoken of as if they involved 



