i.i-.cri lu: AS SOI \('i:mi:\ ts 311 



I )l i;i\(. till' past siiiiiiiicr Mr. \\ allci' ( ii-an^rr (•uiil linicil t lie systciiiat ic 

 exploration (if tli(> iMX'ciir iiiaiiiiiKil l)C(ls comtiu'iiccd in l!)();i w itli the cxplo- 

 nition of the Bridj^cr Basin, and continncd in tlic \\'asliakic, W iiid Kixcr 

 and Bii;- Horn Basins. He secni'cd this ycaf anotlicf xaliiaKIc collection of 

 Lower Kocene fossils iiu'lndin<i- many rare s])i'eiinens. 'rhrou<;li its expedi- 

 tions the Department of \Vrtebrate Pahuontology is aeciuirinj,^ the materials 

 for a complete history of the Eocene mammals of North America, in 

 some respects it is a more complete record than had l)een anticipated, for 

 the more careful and thoroufi:h stratigraphic work has shown tiiat the for- 

 mations of the different basins, instead of being successive in point of time, 

 with gaps between them unrepresented by any fossil-bearing formation, 

 are in point of fact overlapping to an unexpected degree, so that l\v com- 

 bining the records of the different basins we obtain a nearly complete record 

 of Eocene life history in that region. On the other hand the accurate 

 records now kept of the exact level of each specimen have proved that tlie 

 evolution series is less continuous and gradual than had been anticipated. 

 New stages in most races appear stiddenly and displace the old ones, either 

 immediately or little by little, instead of gradually evolving out of them. 

 This fact may be explained in one of two ways. Either the new stage has 

 been gradtially evohed in some other region and reached here by migra- 

 tion; or it evolved not gradually but by sudden changes or "sports" — 

 the method of evolution advocated in recent years by De Vries and others. 

 The careftil study of ^Ir. Granger's collections will supply \ery important 

 evidence on this problem. 



LECTURE ANNOUNCEMENTS 



MEMBERS' COURSE 



The first course of lectures for the season 1911-1912 to Members of the Museum 

 and to persons holding complimentary tickets presented to them by Members will 

 be given in November and December. These lectures deal chiefly with the 

 Museum's explorations of 1910-1911 and will be fully illu.strated by stereopticon. 

 Two only of these lectures roinaiu to he given. 



Thursday eveninsis at 8:1.5 o'clock. Doors open ati7:45. 



December 7 — Mr. Fkank M. Chap.\i.\x, "A Natural Historj- Reconnaissance in 

 Coloml)ia." 



Mr. Chapman entered Colombia at Buenaventura on the Pacific Coast, crossed the 

 western rani^e of the .\ndes into the Cauca Valley, then went down the Cauca River to the 

 northern end of the valley and crossed the Central Andes to the MaRdalena River, which 

 he followed to the Caribbean. Tliis journey of I.jOU miles, throui^h a country of great beauty, 

 was made to secure material for a Habitat Group of Birds in the Tropical Americau Series 

 and as a reconnaissance in the Museum's proposed biological survey of the Cauca Region 

 of Colombia. 



