South Dakota School of Mines 85 



back as earliest Tertiary time, but the fossils are not abundant. 

 The badland formations of the Black Hills region have yielded 

 several forms, but they are fragmentary. They belong to the 

 following families : first, the Erinaceidae, or hedgehogs ; second, 

 the Leptictidae, related to hedgehogs; third, the Soricidae, or 

 shrews ; fourth, the Chrysochloridae, or golden moles. The 

 :single Chysochloridae specimen was obtained from the Lower 

 Miocene south of White river. All of the others are from the 

 Middle Oligocene in or near the Big Badlands. 



The earliest discovery of badland insectivores was made by 

 Dr. Hayden in 1866, near one of the tributaries of White river 

 on the occasion of his last visit to the region. The forms were 

 ■described by Leidy, and consisted of one nearly complete skull 

 •designated as Leptictis haydeni and a fragmentary skull desig- 

 nated as let ops dakotensis. The skulls indicate animals small- 

 er than a mink. In life they were evidently much like present 

 •day hedgehogs, except that they were more primitive. A few 

 years ago the American Museum of Natural History obtained 

 remains of an animal closely related to and slightly larger than 

 let ops dakotensis. Dr. Matthew has named this animal Ietops 

 bulla tus. 



In 1894, Mr. M. S. Farr of the University of Chicago ex- 

 pedition, discovered the facial portion of a skull and lower jaw 

 which upon examination proved to belong to an ancestral shrew. 

 Prof. W. B. Scott, who described the remains, named the ani- 

 mal Protosorex crctssus, in recognition of its very primitive char- 

 acter. This is the first specimen of the shrew family found in 

 the North American Tertiary. 



Remains of a fossil hedgehog were obtained by Dr. Loomis 

 of the Amherst Museum expedition in 1902. This was a frag- 

 mentary skull. It represents the first of the true hedgehogs 

 found in America. Dr. Matthew described the form and gave 

 it the name Proterix loomisi. 



In 1906, Dr. Matthew identified and described meagre, but 

 characteristic, remains of a golden mo\e,Aretoryctes terrenas, 

 among material collected from the Lower Miocene during 

 the summer of that year by Mr. Albert Thomson of the Ameri- 

 can Museum expedition. According to Matthew, true moles 

 fTalpidae) are now found in the subarctic or temperate zones 

 of all the northern continents, but not in or south of the tropics. 

 However, in the south temperate zone, there are animals which 

 have adopted mole-like habits and superficially resemble the true 

 moles to a greater or less degree. The Chrysochloridae or 



