280 



BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 



(ext. mVcarp. ob.) is large, and its tendon, instead of being inserted as 

 normally into the proximal end of metacarpal ii, continues down to the 

 distal phalanges of the supernumerary digits, into which it is inserted by 

 three slips. In two cases this muscle was strengthened by a strong slip 

 from the great extensor of the metacarpus. This is an interesting case 



fix. per// 



^flx.perf. 



II. 



- I" 



Fro. S. — Posterior view of left polydactylc mantis of tlie pig, showing flexor 

 muscles. Jix. per/'., flexor perforatus teudons; Jlx. ptrf ., flexor perforans; i", i'', super- 

 numerary digits. \ natural size. 



of adaptation, and shows what a strong influence the functional capacity 

 of the digits has on the development and structure of tiieir muscles. 



Of the flexor muscles, the perforans (Fig. <S', fix. perf!) gives off a 

 large tendon to the extra digits : this divides, and a branch is inserted 

 into each ungual phalanx. The flexor perforatus {fix. per/.') also sends 

 a large tendon to the extra digits, which bifurcates in the region of the 



