NOTK ON FIJKMONTS COI.LPXTION. 207 



Cycadeoideas, is a poiiil llial al once su.ii.u'cstscithci' a cliaiifje in cliiiialcMii 

 the inlci'N'aJ IhMwccmi ihc tossilizal ion of the Iwo li'roups oi', if they con- 

 linucd 1() exist near (\'i('li oIIkm' in time, tlic pi'escncc about the .lui'assic 

 frcsii-watei' lake of areas with diverse cliinatie conditions. In ttic Black 

 Hills count I'v, at least so fai' as I have noticed, thei'e is likewise a coi're- 

 spoiidinfi difference in the size of the acconipanyinij; silicified tree trunks. 

 Many of the .Vraucai'ioxylons of the upper c\'cad IxmI wore of iininense 

 heiiiht and size. I'ivalintr the Norfolk Island pines of the jiresent. while, on 

 the contrary. 1 have never found markedly larjie tinniks in coiuiection 

 with th(> ( ycadella horizon, although they may occur farthei' west in 

 Wyoming. That any great change took place is not argued. The Cyca- 

 dellas may have grown in dry or arid situations, oi' in a climate like that of 

 Floi'ida, where the dwarf Zamias thrive wliile the Cycadeoideas l)espeak 

 moister and more distinctly tropical conditions. I first pointed out, in 

 a review in the .\merican Journal of Science for May, 1900, j^age 386, 

 the fact that Cycadella might have grown under le.ss favorable conditions. 

 Seward likewise considei's that tJiey may afford suggestions of value con- 

 cerning climatic conditions." 



The microscopic study of the Cycadella series which I have under- 

 taken in conjunction with the study of the Cycadeoidea has not been 

 completed, so that later it will perhaps be possible to discuss such ques- 

 tions as this with more safety. 



In connection with the relative position of Cycadeoidea and (Vca- 

 della, 1 should here mention that, under the direction of Professor Osl)orn, 

 Dr. F. B. Loomis has prepared especially satisfactory sections of the 

 better exposed Jurassic beds as seen farther west in Wyoming.'' While 

 this paper gives more exact information concerning the successive hori- 

 zons and their vertebrate fossils, no mention is made of plant remains. I 

 conclude that the bed Doctor Loomis numbers 22 is the cycad horizon 

 of the Freezeout Hills. 



XOTE ox FKEMONT'S COT.T.EOTION. 



In concluding this account of the known Jurassic floras of the United 

 States, it is well to call attention to the collection made by Fremont on 



"See Nature, October 24, liX)!, p. («:! 



''Oil Jurassic stratigraphy iu soullicastern Wyomiiii^: Bull. Am. Mus. \ut. Jli.st,, \ol. Xl\, Article XII, 

 pp. 189-197. 



