296 NATURAL THEOLOGY. 



unusual an exposure of the globe of the eye re- 

 quires for its lubricity and defence a more than 

 ordinary protection of eyelid, as well as a more 

 than ordinary supply of moisture ; yet the motion 

 of an eyelid, formed according to the common 

 construction, would be impeded, as it should seem, 

 by the convexity of the organ. The aperture in 

 the lid meets this difficulty. It enables the animal 

 to keep the principal part of the surface of the 

 eye under cover, and to preserve it in a due state 

 of humidity without shutting out the light, or with- 

 out performing every moment a nictitation which 

 it is probable would be more laborious to this ani- 

 mal than to others. 



VIII. In another animal, and in another part of 

 the animul economy, the same Memoirs describe 

 a most remarkable substitution. The reader will 

 remember what we have already observed con- 

 cerning the intestinal canal — that its length, so 

 many times exceeding that of the body, promotes 

 the extraction of the chyle from the aliment by 

 giving room for the lacteal vessels to act upon it 

 through a greater space. This long intestine^ 

 wherever it occurs, is in other animals disposed in 

 the abdomen from side to side in returning folds. 

 But in the animal now under our notice the mat- 

 ter is managed otherwise. The same intention is 

 mechanically effectuated, but by a mechanism of 

 a different kind. The animal of which I speak is 

 an amphibious quadruped, which our authors call 

 the alopecias or sea-fox. The intestine is straight 



