INSECTIVORA 



the young generally from four to 



PIG. 290. Skeleton of Mole x | (lower jaw 

 removed to show base of skull), c, Calcanetim ; 

 c.h., clavicular articulation of the humerus ; cl., 

 clavicle; .c, external condyle of humerus; /., 

 femur ; fb, fibula ; /c, falciform bone (radial sesa- 

 moid) ; h, humerus ; i.c, internal condyle of 

 humerus ; il, left ilium ; i.p, ramus of the ilium 

 and pubis ; is., ischium ; l.d, ridge of insertion of 

 latissimus dorsi muscle ; l.t, lesser trochanter ; m, 

 manubrium sterni ; o, fourth intercentral ossicle ; 

 ol, olecranon ; p., pubis widely separated from that 

 of the opposite side ; pa., patella ; p.m., ridge for 

 insertion of pectoralis major muscle ; pt., pectineal 

 eminence ; r, radius ; rb, first rib ; s, plantar sesa- 

 moid ossicle corresponding to the radial sesamoid 

 (os falciforme) in the manus; sc., scapula; s.h., 

 scapular articulation of the humerus ; t, tibia ; u, 

 ulna. 



six in number which are 

 brought forth in about six 

 weeks, quickly attain their 

 full size. 



The Mole exhibits in the 

 whole of its organisation a 

 perfect adaptation to its 

 peculiar mode of life. In 

 the structure of the skeleton 

 (Fig. 290) very striking de- 

 partures from the typical 

 mammalian form are notice- 

 able! Thus the presternum 

 is so much produced anteriorly 

 as to extend forward as far as 

 a vertical line from the second 

 cervical vertebra, carrying 

 with it the very short and 

 almost quadrate clavicle, which 

 is articulated with its anterior 

 extremity and distally with 

 the humerus ; being also con- 

 nected ligamentously with the 

 scapula. The fore limbs are 

 thus brought opposite the 

 sides of the neck, and from 

 this position a threefold ad- 

 vantage is derived : in the 

 first place, as this is the 

 narrowest part of the body, 

 they add but little to the 

 general width, which, if in- 

 creased, would lessen the 

 power of movement in a 

 confined space ; secondly, this 

 position allows of a longer 

 fore limb than would other- 

 wise be possible, and so in- 

 creases its power; and, thirdly, 

 although the entire limb is 

 relatively very short, its an- 

 terior position enables the 

 animal, when burrowing, to 

 thrust the claws so far for- 

 ward as to be in a line with the 

 end of the muzzle, the import- 



