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University of California Publications. [Geology 



fissure is almost choked by large fallen blocks. From the posi- 

 tion of the sloth remains beneath some of these blocks it was 

 evident that many of the latter had reached their present rest- 

 ing place at a later date than the bones. The abrupt descent 

 precludes the idea that the animal wandered into the cave and 

 there died. The best explanation of its presence seems to be 

 that it was killed by a fall into the cave. 



Through the kindness of Dr. C. R. Eastman, the specimen in 

 the Harvard Museum was borrowed for examination. On the 

 accompanying label it was stated that fragments of human 

 crania were found associated with the mandible. Several 

 human skeletons were found on the surface of the earth slope 

 mentioned above, but these were probably comparatively recent 

 Indian interments, while the sloth remains were from a much 

 deeper part of the cave. Some of the human bones were 

 incrusted with a very thin shell of stalagmite. It seems once to 

 have been the custom of the Indians in this region to cast the 

 bodies of the dead into such natural pits and caves as the region 

 afforded. The human remains in Mercer's cave were apparently 

 introduced in this way. 



The ground-sloth bones collected are those of a young animal 

 and differ in several respects from Megalonyx jeffersonii with 

 which some of the dimensions compare favorably. 



Two views of the mandible are given on Plate 21. The jaw 

 is smaller than the corresponding element in Megalonyx jeffer- 

 sonii, but this is due in part to the youth of the animal, in 

 which the epiphytic elements were still distinct. The bone 

 is invested with a layer of stalagmite which increases its size 

 slightly. The second and fourth molars on the right side have 

 the triturating surfaces broken. Some of the teeth are more or 

 less coated with stalagmite. The canine molars are not much 

 curved. The external dentine layer only could be distinguished. 

 The internal convex rib is not cpiite central, and the concavity 

 bounding it posteriorly is deeper than the anterior one. 



A comparison of the dimensions tabulated on page 159 with 

 the measurements of the mandible of Megalonyx jeffersonii 

 given by Leidy,* shows that while the jaw is shorter and shal- 



* J. Leifly, A memoir on the Extinct Sloth Tribe of North America 

 Smithsonian Contrib., Vol. VII. 



