346 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1918. 



acteristic of the order is the relative slenclerness and elongation of the 

 stem and the frequency with which it branched, often dichotomously. 



It is not possible to consider the various foliar types in the limits of 

 the present paper, a subject requiring much study and never ade- 

 quately discussed, and only a few of the more representative types will 

 be mentioned. Among these one of the most remarkable is the genius 

 Wielandiella from the Rhaetic of Sweden. Wielandiella had an elon- 

 gated slender stem not over 2 centimeters in diameter, with repeated 

 dichotomies, prevailingly naked except in the region of the forks, 

 where it bore spirally arranged, rather reduced fronds of theNilssonia 

 or Anomozamites types. In each fork was a subsessile fructification 

 surrounded by bracts. These fructifications are met with in two 

 forms, probably representing different ages and states of preservation. 

 In the one it consists of a small pyriform axis separated from the 

 peduncle by a swollen striated collar bearing oval microspores on the 

 surface of greatly reduced scalelike sporophylls. Ovulate structures 

 on the pyriform axis appear to have been vestigial. In the second 

 type the axis is hidden by the linear bracts but its surface reveals a 

 regular pattern of interseminal scales between which the micropvlar 

 tubes project, indicating an ovulate organization like that of the 

 cycadeoids and Williamsonia. 



Another old genus is the Rhaetic genus Cycadocephalus, also from 

 Sweden, and based on impressions of a large fructification 10 centi- 

 meters long and 7 centimeters in diameter. The peduncle is slender 

 and shows no leaf or bract scars. No trace of a central ovulate re- 

 ceptacle is discernible, the head consisting of a cluster of linear 

 microsporophylls with a keellike midrib on their inner faces, and 

 bearing on either side of this midrib linear pointed synangia. 



A third Rhaetic genus is Weltrichia from Franconia, based upon 

 a funicular fructification, the, cup of which was formed by the con- 

 crescent bases of about a score of broadly linear microsporophylls, 

 the whole 10 centimeters in length and centimeters in diameter. 

 The free lanceolate apical portions of these bear linear appendages 

 5 to R millimeters long attached to their inner faces, comparable 

 with the synangia of Cycadocephalus. No traces of ovulate struc- 

 tures are known, so it can not be determined whether either Cyca- 

 docephalus or Weltrichia were unisexual or bisexual. An elaborate 

 account of Weltrichia by Schuster, largely imaginative, supplies a 

 remarkable assemblage of features that are best ignored until cor- 

 roborated by some reliable student. 



As previously mentioned, a variety of frond genera of late Tri- 

 assic, Jurassic, and Lower Cretaceous ages are found from Japan 

 and New Zealand on the east to California and Alaska on the west, 

 and from Franz Joseph Land. Spitzbergen, and Greenland on the 

 north to Graham Land on the south. No continent is without an 



