664 S. W. WILLISTON 



THE LIMBS OF LYSOROPHUS 

 BY MARIAN FINNEY 



In 1908 Dr. Williston discovered in a nodule containing a 

 series of Lysorophus vertebrae and ribs limb bones which he 

 believed belonged with them, but he was not sure that they might 

 not have been accidental intrusions from some other small, unde- 

 tected amphibian. To determine, if possible, whether Lysoro- 

 phus really is a limbless amphibian or not, Dr. Williston re- 

 quested me to study carefully the material of the collections of the 

 University of Chicago coming from Texas. As a result of this 

 study I am able to say with assurance that the evidence proves, 

 I thing conclusively, that Lysorophus does possess limbs, though 

 it has been impossible to determine whether the limbs are the 

 front or the hind, or whether indeed both front and hind. 



The limbs in life were evidently loosely attached to the ver- 

 tebral column, and were easily separated and lost ; and the bones 

 themselves are so minute that, once separated from the skeleton 

 they would hardly be detected, or if detected correctly recog- 

 nized. Of the two hundred nodules examined, containing more 

 or less of the skeleton of Lysorophus, I find fifteen containing limb 

 bones, the most of them isolated; only a few with more than 

 one bone associated. 



The best of these specimens consists of a femur, tibia, fibula, 

 two metatarsals and two phalanges all related. I assume that 

 the limb is the hind one because of the shape of the bones only. 

 The femur is 10.5 mm. in length, hollow throughout, with a 

 rather slender shaft, and moderately expanded ends; its ends 

 are mere shells of thin bone, easily crushed. The tibia and fibula 

 are 6.5 mm. in length, or about three-fifths the length of the 

 femur and, like it, are hollow. The tibia is thickset, the ends 

 less expanded than those of the femur. The fibula is slender, 

 and lies close beside the tibia. Beyond these epipodials are 

 two bones which doubtless are metatarsals, though not much 

 shorter than the tibia and fibula; they measure 5 mm. in length. 

 Beyond these are two small bones which seem to be phalanges, 

 lying one at the end of the other, each about 1 mm. in length. 



