April 8, 1904.] 



SCIENCE. 



58J 



At the regular meeting, February 15, Vice- 

 President James F. Kemp presiding, the secre- 

 tary read a letter from Dr. J. G. Aguilera cor- 

 recting a statement in one of the papers pre- 

 sented at the December meeting of the acad- 

 emy, as reported in Science, regarding the 

 great Bacubirito meteorite of Mexico. Dr. 

 Aguilera called attention to the fact that this 

 meteorite was discovered in July, 1871, as 

 was stated by A. del Castillo in ' Catalogue 

 descriptif des Meteorites,' Paris, 1889. It 

 was described by F. Sosa y Avila in Minero 

 Mexicano in 1890, and afterward was visited 

 by Signor Buelna as a commissioner of the 

 Geological Institute of Mexico for the pur- 

 pose of calculating the cost of transporting it 

 to the City of Mexico. In connection with 

 this expedition Buelna made several drawings 

 and photographs of the great mass of iron. 

 Through the Geological Institute Professor 

 H. A. Ward received exact information as to 

 the locality of the meteorite and then visited 

 it, removing the earth from about it and 

 making new lahotographs. Professor Ward's 

 recent articles (1903) have drawn renewed 

 attention to this enormous meteoric mass, but 

 the credit of original discovery and descrip- 

 tion belongs to the Mexicans. 



The program of the evening comprised two 

 papers, abstracts of which follow : 



The Occlusion of Igneous Boclc within Meta- 

 morphic Schists: Dr. Alexis A. Julien. 

 The term ' inclusive ' is commonly applied, 

 by the petrographer, to ordinary dikes of 

 igneous rock, surrounded by beds of sediment- 

 ary rocks or of crystalline schists, intersect- 

 ing them or intervening between their folia- 

 tion planes. But for similar masses cut loose 

 from all connection with the underlying 

 magmatic source, swallowed iip within strata 

 of crystalline schists, and experiencing all 

 stages in the process of reaction and final ab- 

 sorption, during metamorphic change, an- 

 other term seems to be called for, ' occlusion,' 

 signifying shut or sealed up beyond escape. 

 Although the word is borrowed from the 

 physicist, this can produce no confusion when 

 applied to petrographic phenomena. Occlud- 

 ed igneous rocks may belong to either the acid 

 or the basic class, as illustrated respectively. 



on Manhattan Island, by the earlier intrusions 

 of pegmatite, never found as intersecting 

 dikes, and by the intercalated sheets of diorite- 

 schist. Occlusion is usually attended by 

 mechanical and chemical processes. The 

 former consist of thinning or thickening of 

 igneous masses caught between the folia of 

 schists during erogenic movements into len- 

 ticular masses ; the crumpling and corrugation 

 of sheets, and even rolling into cylinders; and 

 the forcing of the pasty masses along foliation 

 planes, in the form of intercalated or ' sec- 

 ondary ' dikes. The chemical processes usu- 

 ally consist of micaceous alteration and ulti- 

 mate absorption by disintegration and dis- 

 semination through the surrounding country 

 rock. 



In discussing this paper. Professor Kemp 

 spoke of the value of the interpretation to 

 those who have studied the region. 



Outlines of the Continents in Tertiary Times: 



Dr. W. D. Matthew. 



The author presented a series of world-maps 

 showing the hypothetical outlines of the con- 

 tinents during the Pleistocene, Pliocene, 

 Miocene, Oligocene, later Eocene and at the 

 opening of the Tertiary period, as contrasted 

 with the modern conditions. The series was 

 got up for use in the Hall of Fossil Mammals 

 in the American Museum of Natural History, 

 to illustrate the geographical distribution of 

 different groups of mammals during the suc- 

 cessive epochs of the Tertiary and Quaternary. 

 It is intended to represent a somewhat con- 

 servative view of past changes in world geog- 

 raphy, and is regarded as a working hypoth- 

 esis, based on our present knowledge of 

 geology, paleontology and zoology, especial 

 consideration being given to the mammalian 

 paleontology. 



The former extension of the Antarctic con- 

 tinent, so as to join Australia with South 

 America, is regarded as occurring at the end 

 of the Cretaceous period and is represented 

 in the first map of the series. The connec- 

 tion with South Africa is regarded as too 

 problematic to place on the map. The Eocene 

 map shows the extreme of Tertiary submerg- 

 ence of the continents which are represented 

 as forming six isolated land masses. The 



