ON A PECULIAR MONSTROSITY IN A FROG. 



GEORGE WAGNER, 

 DEPARTMENT OF ZOOLOGY, UNIVERSITY OF WISCONSIN. 



About three years ago a student, Mr. F. L. Conover, brought 

 me a remarkable specimen of Rana pipiens, which he had found 

 among the specimens at the biological laboratory of the Madison 

 High School. The frog was alive. It measured fifty-two milli- 

 meters body length and was apparently in full vigor, its death 

 being caused by an overheating of my office at a time when I had 

 to be unexpectedly absent for several days. 



The remarkable character of this specimen consists in the 

 presence of three extra limbs extending caudad from the region 

 of the sternum, two on the right and one on the left side. It is 

 very evident that they are attached to an extra basal piece 

 overlying the sternum. All three are more or less imperfect, 

 so that I find it impossible to determine whether they represent 

 arms or legs, or both. Each has four malformed digits, and 

 each shows a thickening indicating the location of the joint 

 between the proximal and distal parts of the limb, the elbow or 

 knee. All are pigmented on the surface away from the frog, 

 with no pigment on the opposite surface. The accompanying 

 photograph (Fig. 2) and radiograph (Fig. i) of the specimen 

 illustrate better than any verbal description the actual con- 

 ditions present. 



Monstrosities in nature involving the hind legs are not un- 

 common in the frog, but those involving the fore limbs are 

 apparently rare. The only one known to me is one figured by 

 Sutton ('92, p. 112, Fig. 60), involving the presence of an extra 

 leg on the left side. There is a case in the human being, often 

 quoted, shown in Fig. 3; I have been told about another closely 

 similar case exhibited in this country several years ago, but I 

 have not been able to get exact information concerning it. 



Dr. F. R. Lillie kindly called my attention to a very important 

 paper by Tornier (105) which I would otherwise have overlooked. 



