564 



CHORDATA 



Order II. Insectivora. 



Of all living mammals the insectivores stand nearest to the ]iriniilive type, 

 the order dating back to the eocene. The sharjvpointed teeth (secloiial), 

 adapted for insect food vary t;reatly in number in the different families (moles, 



^li:i; shrews, -i.Viii), as also does the replace- 

 ment, since many forms retain the milk denti- 

 tion for a long time or never lose it, while the 

 shrews lose it very early. They have the process 

 at the angle of the lower jaw, a iirimitive brain, 

 a uterus bicornis or one divided throughout. 

 There are frequently scales on the tail among 

 the hairs; the clavicle is present; usually five 

 clawed toes. The animals which as a rule are 

 small, with soft hair, usually have a proboscis-like, tactile snout. 



The Erin.\cid.e, Old World hedgehogs, arc spined; the Soricid.k, or shrews 

 {Sonw* Blariiia*), are mouse-like, as are the allied T.\lpid.e, or moles (Scalops* 



Fig. 012. — Skull of S"rcx ^frora 

 Ludwig-Leunis). 



Fig. 6ij. — Skeleton of bat leafier Urchin'). 



Condvhira* star-nosed mole"), which burrow in the earth and ha\'c the eyes more 

 or less rudimentary. Some authors ]ilace here C/\i/c,i/);7/;C(».s- of the East Indies, 

 •which has a similar membrane and sailing powers as the tiying squirrels. It 

 also resembles the bats and lemurs. 



Order III. Chiroptera. 



The bats arc the only mammals which actually fiy, and this at once charac- 

 terizes them. The fiying membrane {pcitagiuiii), a thin fold of skin, begins at 

 the tail, includes the lower extremities to the foot, and extends thence to the 

 fingers, leaving the thumb free. Fingers 2-5 are enormously elongated and 

 support the membrane. Since flight requires strong muscles, the sternum 

 develops a small keel for the attachment of the large pectoral muscle. In 

 connexion with the flying powers the clavicle is strong. The patagium is very 

 sensitive; blinded bats can fly among all kinds of obstacles without disturbing 

 them. The enormous ear conchs and a noticeable nose leaf, widely distributed 

 through the group), also have marked tactile powers. In the pectoral position 



