May 22, 1914] 



SCIENCE 



761 



Irwin; Meyer's Theorie benachbarter Geraden 

 iind ein verallgemeinerter KriimmungsbegTitJ, 

 by E. B. Cowley; Hilbert's Grundlagen der 

 Geometrie and Grundziige einer allgemeinen 

 Theorie der linearen Integralgleicbungen, by 

 T. H. Gronwall; Lebon's Gabriel Lippmann, 

 Iforitz's College llatbematics Notebook and 

 College Engineering INotebook, and Harris's 

 Gravitation, by E. B. Wilson; "Notes"; and 

 '■' New Publications." 



The April number of tlie Bulletin contains : 

 '•' An unpublished theorem of Kronecker re- 

 specting numerical equations," presidential 

 address, by H. B. Fine ; " Two convergency 

 proofs," by Arnold Emch ; " Some properties 

 of the group of isomorphisms of an abelian 

 •■roup," by G. A. Miller; Eeview of Landau's 

 Handbuch der Lehre von der Verteilung der 

 Primzahlen, by T. H. Gronwall; Eeview of 

 Fisher's Purchasing Power of Money, by E. B. 

 Wilson ; " Shorter Notices " ; Clebsch-Linde- 

 mann's Geometrie, by Joseph Lipka; Weyl's 

 Die Idee der Eiemannschen Flache, by F. E. 

 Moulton ; " Notes " ; and " New Publications." 



The May number of the Bulletin contains: 

 Eeport of the February meeting of the society, 

 by F. N. Cole ; " A non-enumerable well- 

 ordered set," by A. B. Frizell ; " Note on the 

 Fredholm determinant," by W. A. Hurwitz ; 

 •' Time as a fourth dimension," by E. C. Archi- 

 bald; Eeview of Biitzberger's Bizentrische 

 Polygene, Steinersche Kreis- und Kugelreihen 

 »nd die Erfindung der Inversion, by Arnold 

 Emch ; " Shorter Notices " ; Loria's Poliedri, 

 Curve e Superficie secondo i Metodi della 

 Geometria descrittiva and Darstellende 

 Geometrie, zweiter Teil, by Virgil Snyder; 

 Czuber's Differential- und Integralrechnung, 

 by L. W. Dowling; Ciani's Lezioni di Geom- 

 etria proiettiva ed analitica, by E. B. Cowley ; 

 Hessenberg's Transcendenz von e und tt and 

 Bolza's Variationsreehnung, by T. H. Gron- 

 wall; Pioard's Das Wissen der Gegenwart in 

 Mathematik und Naturwissenschaft, by J. B. 

 Shaw; Sturm's Maxima imd Minima in der 

 elementaren Geometrie, by J. V. McKelvey; 

 Norris and Craigo's Advanced Shop Mathe- 

 matics, by P. F. Smith ; Czuber's Wairschein- 



lichkeitsrechnung, by H. B. Phillips; Lord 

 Kelvin's Mathematical and Physical Papers, 

 volumes IV., V. and VI., and Love's Problems 

 of Geodynamics, by E. B. Wilson; Annuaire 

 pour I'An 1914 publie par le Bureau des 

 Longitudes, Combebiac's Les Actions a Dis- 

 tance and Abbe's Mechanics of the Earth's 

 Atmosphere, by E. W. Brovm ; " Notes " ; 

 and " New Publications." 



SPECIAL ARTICLES 



THE SYSTEMATIC POSITION OP THE MYLODONT 

 SLOTHS FROM RANCHO LA BREA ^ 



In the excavation work carried on by the 

 University of California in the Pleistocene of 

 Eancho La Brea, a considerable percentage of 

 the material obtained represents ground-sloths 

 of the mylodont group. Twenty-seven skulls, 

 representing the family Mylodontidas, are now 

 in the collection of the department of pale- 

 ontology. Of these, nineteen are well preserved 

 and show the dental series on both sides. 

 Many lower jaws are also available, several of 

 which are associated with the skulls. In a 

 preliminary consideration of this extensive 

 series of specimens, certain suggestions as to 

 the relationship of some of the mylodont 

 genera have presented themselves. It seems 

 desirable, therefore, to make this information 

 available for other students of the group. 



The writer is indebted to Professor John 0. 

 Merriam for kind assistance during this study. 



The genera Mylodon and Paramylodon, to 

 which the Eancho La Brea material has previ- 

 ously been referred, are the members of the 

 family Mylodontidse definitely recognized in 

 the North American Pleistocene. A frag- 

 mentary lower jaw, originally described by 

 Harlan from Big Bone Lick, Kentucky, was 

 referred to Mylodon by Owen in 1840. In 

 190.3 Brown- established the genus Para- 

 mj/lodon on a skull and lower jaw with asso- 

 ciated skeletal material obtained from Pleis- 

 tocene deposits near Hay Springs, Nebraska. 



1 Bead at the fifth anmial meeting of the Paleon- 

 tological Society, Princeton, N. J., Jamiary 1, 1914. 



2 Brown, B., Bull. Amer. Mus. Nat. Hist., Vol. 

 XIX., Art. XXII., pp. 569-583, 1903. 



