404 CARNEGIE INSTITUTION OF WASHINGTON. 



Besides completing the study of the collections mentioned in the pre- 

 ceding report, the results of which appear in the Proceedings of the 

 United States National Museum, the wiiter has studied the interesting 

 collection made in Arizona and a small collection made in Oregon. All 

 the collections referred to have yielded new species. The range of the 

 hairy mammoth, Elephas primigenius, has been extended into Tennes- 

 see and into Texas near San Antonio. 



Wieland, G. R., Yale University, New Haven, Connecticut. Associate in 

 paloeontologij. (For previous reports see Year Books Nos. 2-4, 6-9, 

 11-18.) 



In earlier reports, especially those for the years 1917-1919, the 

 scope of the palseontologic investigations centering about the cyca- 

 deoids, their relatives, and their derivatives, is briefly brought into 

 view. It should be emphasized, however, that throughout the entire 

 course of these studies, now extending over a period of 20 years, a 

 great aim has been to secure new material afield, affording evidence 

 of the origins of seed plants. The zoologist, the botanist, the ecologist 

 finds at his feet vast categories of fact requiring the correlations that 

 make new discoveries a certainty. The assemblage of most biologic 

 data thus goes on rapidly, and usually the picture is complete, whatever 

 the interpretation. But fossil plants are brought together slowly, 

 only as the horizons which yield them are searched with renewed care. 

 Then, between the more striking ''finds," laboratory examination and 

 comparative studies are pushed towards the limits of the evidence in 

 hand. Fortunately, the actual evidence secured is not always meager. 

 As noted last year, the coniferous stem material now accumulating is 

 much in advance of present laboratory study. 



In the case of the gymnosperm imprints and casts, the greatest need 

 is for prolonged search of Triassic and Jurassic fresh-water terranes. 

 It is now evident that the lower half of the Mesozoic holds the transi- 

 tion forms between the gymnosperms and early dicotyls; and, as 

 already insistently pointed out, it is also pretty certain that, with the 

 plastic types neither few nor obscure, the course of change from period 

 to period goes on in entire floras, resulting in a certain prevailing cast 

 of plant life, or simply those successive stages of development already 

 more or less in view, but not well understood because of the dearth of 

 intermediate types. 



The outstanding result of the cycad studies has not been so much 

 the demonstration of floral organization in a few forms (about a score). 

 It is rather that broader study, which has in some adequate measure 

 brought out the real nature of the cycadeoid cast of Mesozoic vegeta- 

 tion, so that it is now possible to see that the cycadeoids are not 

 specialized as hitherto believed, but of generahzed floral, leaf, and stem 

 type, and that they must have dominated not merely in numbers, but 



