Art. IV.] 



Hill, A DcforDicd Chick. 



31 



The structural differences between these legs are contrasted 

 in figs. I, 2, 3, 4, 5 and 6. The abnormal leg has only three toes 

 and no trace of a fourth. The normal leg has four toes. 



The table giv^en above renders a detailed description un- 

 necessary. I must mention however that in the abnormal leg 

 the first and second bones of the third toe have fused, and that 

 the femur of the abnormal leg contains a conspicous spine for 

 the insertions of muscles and that the nails of the abnormal leg 

 are relatively larger than those of the other leg. 



The resemblance of this deformed leg to the normal leg of 

 the auk is both astonishing and instructive. The following 

 table diplays that comparision. 



THE niVING lilRDS. — THE AUKS. 

 Ck a ra c/e n sties . 



1. Backward po.sition of their 

 legs. 



2. The toes are either webbed or 

 lobed. 



3. The absence of one toe. 



4. The tibia relatively short. 



5. The toes have claw-like nails. 



DEFORMED CHICK. 



Ch a racteristics . 



1. Backward position of the de- 

 formed leg. 



2. The toes of the deformed leg 

 are webbed. 



3. The absence of one toe. 



4. The tibia relatively short, com- 

 pared with the tibia of the normal 

 leg. 



5. Have claw-like nails. 



In drawing inferences concerning deformities one must not 

 jump to hasty conclusions. That this deformed leg resembles 

 the normal legs of the diving birds there can be no doubt and 

 to the writer this seems to be an unilateral reversion. Even 

 though this conclusion should not stand the test of time, it is 

 thought that the above description of the facts in the case will 

 be of value to students of variations. 



BIOLOGrCAL LABORATORY OF CLARK UNIVERSITY, 

 SO. ATLANTA, GA. 



