934 



SCIENCE 



[N. S. Vol. XXVIII. No. 730 



rence is in the oxidized portion of a contact meta- 

 morphic deposit in limestone at the contact with 

 quartz-porphyry. A number of 'carloads of this 

 mineral were shipped in 1905. The mineral was 

 identified by analysis. 



Lines of Inference in Paleogeographio Studies: 



Mr. Bailey Willis. 



The primary diflficulty in attempting to draw 

 a map of North America, for example, to repre- 

 sent the continent as it was during a given period, 

 is to select facts which may be assumed to have 

 had approximate synchronism. The New York 

 Trenton, for instance, can not be narrowly cor- 

 related with an equivalent in the Mississippi 

 Valley region or in the Nevada basin, even where 

 the sequence of Ordovician strata is unbroken 

 and the Trenton interval is represented by some 

 part of the sediments. Hence, in treating a large 

 area, it becomes necessary to accept approximate 

 correlations and to present a sequence of geo- 

 graphic changes or a tendency toward a certain 

 geographic state, rather than a definite state 

 which may have been attained at a definite time. 

 The data of paleogeography are: (1) the criteria 

 of overlap and shore sediments to determine 

 coasts; (2) the distribution of marine sediments 

 to determine known seas; (3) the arrangement 

 of oceanic depths, negative continental elements 

 and positive continental elements, to determine 

 possible extensions of the more or less probable 

 lands and seas. 



From this consideration of stratigraphic data 

 there results in any case a certain possible dis- 

 tribution of lands and seas which may be tested 

 in the following manner. Under the supposed 

 conditions and under general laws of atmospheric 

 and oceanic circulation, ocean currents presumably 

 took certain courses. If the lithologic and faunal 

 facies of marine deposits (local modifying influ- 

 ences apart) are determined primarily by oceanic 

 currents and distributed accordingly, then the 

 courses of the currents deduced from the supposed 

 arrangement of lands and seas should lead to a 

 distribution of facies corresponding broadly with 

 the observed deployment of facies over the con- 

 tinent. 



Applying these criteria to a definite problem, 

 it is suggested that the marine circulation during 

 Trentonian time developed into a central epicon- 

 tinental current, which flowed northward from 

 the Gulf of Mexico; bathed the shores of Colorado 

 on the west and Appalachia on the east; spread 

 around the Ozark and Wisconsin islands, and 

 penetrated across the Laurentian region to the 



Arctic. Return currents flowed southward along 

 the St. Lawrence and Champlain trough and con- 

 tinued along the shore of Appalachia between the 

 northward-flowing current and the land and their 

 effect extended to Alabama and Arkansas. A 

 similar current flowed south along the trough of 

 the Rocky Mountains in British Columbia at 

 least as far as the forty-ninth parallel. The 

 distribution of two very distinct Ordovician facies, 

 the Galena-Trenton and the Normanskill facies, 

 appears to correspond with the deductions re- 

 garding currents. 



Philip S. Smith, 



Secretary 



THE TOEEEY BOTAOTCAL CLUB 



The first meeting of the season, held at the 

 Museum of Natural History, on October 13, 1908, 

 was called to order at 8:20 p.m. by Dr. Howe in 

 the absence of other ofiicers. Mr. George V. Nash 

 was elected chairman. There were fourteen per- 

 sons present. The resignation of Dr. C. Stuart 

 Gager as secretary of the club, occasioned by his 

 removal to the University of Missouri, was read, 

 and accepted with regret, after an expression of 

 the value of his services to the club. 



The scientific program consisted of informal 

 reports on field observations by members. Pro- 

 fessor F. E. Lloyd was called upon first and 

 spoke of his recent experiences in Mexico. He 

 exhibited field notes and photographs of cacti col- 

 lected largely in northern Zacatecas, Mexico; in a 

 restricted region, about sixty species are found. 

 Four species of Opuntia are reported to be new: 

 there were no species of Echinocereus. Owing to 

 the fact that cacti in conservatories often exhibit 

 very different behavior from that in their natural 

 habitat, the importance of such field study of the 

 group is to be emphasized. 



Professor Lloyd then spoke on the bionomics of 

 Parthenium argentatum, known in Mexico as 

 guayule. From this plant a large amount of 

 commercial rubber is obtained; the rubber occurs 

 in masses in cells of the pith, medullary raya 

 and cortex, and is extracted by mechanical means. 

 In addition to reproducing freely by seed, there 

 is an interesting method of vegetative reproduc- 

 tion. The plant has, besides a tap-root system, 

 long and slender horizontal roots near the surface, 

 from which new shoots arise and produce new 

 plants at a distance of a meter or more from the 

 main plant. There may be from two to six of 

 these shoots arising from one point, producing 

 such a different habit that such plants may be 



