CHORD ATA — VERTEBR ATA — MAMMALS 379 



Order j, Insectivora 



Small mammals, eating worms and insects, — (whence the 

 name). 



These have a low type of brain and occur from the Jurassic 

 to the present, including the extinct sub-order of the Jurassic 

 Pantotheria. The living families of the moles, shrews and hedge- 

 hogs have existed since the Eocene. 



Order 4, Chiroptera {Bats) 



Mammals with the fore limbs modified to form -svings by the 

 development of a broad web between the greatly elongated 

 fingers (usually the second to fifth) and the sides of the body 

 and the hind limbs (hence the name from Greek cheir, a hand, 

 + pteron, a wing). Breastbone with a keel for attachment of 

 flying muscles. 



This order is known from the basal Eocene of Colorado to the 

 present, and now includes the fruit-eating bats of the tropics 

 of the Eastern Hemisphere and the insect-eating bats so abun- 

 dant throughout the world. 



Order 5, Carnivora {Cats, Dogs, etc.) 



Fur-covered, flesh-eating mammals (whence the name from 

 Latin carnis, flesh, + vorare, to devour) ; all teeth have cutting 

 edges. 



This order is known from the Eocene to the present. It 

 includes: (i) the extinct primitive Creodonta (Basal Eocene to 

 Lower Oligocene, mostly of North America, but also of Europe 

 and Africa). These are such generalized types that they are 

 only w^ith difficulty distinguished from the Eocene Insectivora 

 and Ungulata. As they do not possess well-developed sectorial 

 teeth (see below under Fissipedia), they are not perfected as 

 flesh eaters. Examples of these are Mesonyx and Patriofelis 

 (Fig. 163, 2-4), both from the Middle Eocene (Bridger) of the 



