UNIVERSITY OF CALIFORNIA PUBLICATIONS 



BULLETIN OF THE DEPARTMENT OF 



GEOLOGY 



Vol. 10, No. 11, pp. 165-178, plates 3-4 Issued April 17, 1917 



FURTHER OBSERVATIONS ON THE SKULL 

 STRUCTURE OF MYLODONT SLOTHS 

 FROM RANCHO LA BREA 



BY 



CHESTER STOCK 



CONTENTS 



PAGE 



Introduction 165 



Cranium , 16G 



Mandible 168 



Dentition 168 



Mylodon harlani tenuiceps, n. subsp 171 



Conclusions 174 



INTRODUCTION 



Opportunity has recently been afforded the writer to examine 

 the very extensive series of mylodont skulls from Rancho La Brea 

 contained in the collections of the Museum of History, Science and 

 Art of Los Angeles. This series consists of thirty-two crania and a 

 number of mandibles, for the most part well preserved, together with 

 other skull material not in as favorable a state of preservation. The 

 splendid collection at the Museum in Los Angeles rivals in wealth of 

 material the great collections of Pampean ground-sloths in South 

 American museums. 



In examination of the Los Angeles series of skulls a number of 

 interesting points presented themselves which were not touched upon, 

 or were but little discussed, in the preliminary report by the writer 1 

 on the University of California series. Several of the skulls examined 

 were found to differ in certain features from the broad type character- 



1 Stock, C, Skull and dentition of the mylodont sloths of Rancho La Brea, 

 Univ. Calif. Publ., Bull. Dept. Geol., vol. 8, pp. 319-334, 1914. 



