2^S 



The Journal of Heredity 



A LIVING DOUBLE-HEADED CALF 



This calf was born in Kansas on March 12, I'-fil. A rcniarkal^le fact is that it has lived and 

 functions sufficiently to sustain apparent normal life. The double head is its only abnormal fea- 

 ture. It is able to eat through either of the two mouths, but only two eyes are useful, and these 

 are situated on the outer sides of the double head. Thus it cannot see directly forward without 

 turning the head sideways, and this causes very awkward movements in walking. (Fig. 21.) 



TRIVALEXT LOWER JAW 



The division of the ventral part 

 of the head is less complete than is that 

 of the dorsal. The lower lips are 

 divided as are the upper lips, but the 

 jaws are fused and crowded and, in 

 general, very abnormal. This fused 

 condition is so marked that the entire 

 compound lower jaw mo\es in unison. 

 The right side is much nearer normal 

 than the left. The lower incisors, for 

 example, are straight and in a normal 

 position except those on the left side, 

 which are quite irregular owing to the 

 crowded condition at the median 

 fusion line. 



The left lower jaw, howe\er, shows 

 signs of further division. There are 



parts of two sets of incisors. The 

 most interesting feature in this con- 

 nection is the fact that the two incom- 

 plete lower jaws on the left side are not 

 closely articulated but ha\e a slightly 

 independent mo\ement. When the 

 calf chews, the jaw of the right head and 

 the right jaw of the left head mo\e 

 solidh- together since the\- were fused 

 b>- ossification, while the incomplete 

 jaw on the left side of the left head has a 

 slightly independent action. This, 

 however, is not great enough to inter- 

 fere with mastication on that side. 



The nuiscular partition between the 

 two mouths is complete but there are 

 no indications of a division l)etween the 

 two rudimentar>' jaws of the left side. 



