FOSSIL CYCADEAN TRUNKS FROM WYOMING 261 



nostic, and to show the differences in the different genera I 

 will reproduce the descriptions of different authors of these 

 generic characters, translating where necessary : 



Bucklandia : scarred-areolate by the scars of the spadices, scales, and 



petioles (Carruthers) . 

 Yatesia : covered by the scales and persistent bases of the petioles 



(Carruthers). 

 Williamsonia : scarred-areolate by the markings of the deciduous peti- 

 oles (Carruthers). 

 Bennettites : covered with the persistent bases of the petioles (Car- 

 ruthers). 

 Mantellia : same as Bennettites (Carruthers. This was Brongniart's 



name of Cycadeoidea which Carruthers adopted). 

 Raumeria : densely covered or scarred by the persistent bases of the 



petioles and stipule-shaped, connate scales (Carruthers). 

 Fittonia : covered by the scales and persistent, large, geniculate bases 



of the petioles (Carruthers). 

 Crossozamia : covei-ed by the short, subimbricate bases of the petioles 



(Carruthers). 

 Clatharia : marked by transverse rhombic or irregularly pentagonal 



and hexagonal scars of leaves truncated above the base (Carruthers). 

 Cycadeoidea : enveloped by the basilar remains of the leaves, rhom- 



boidal in cross-section (Schimper). ' 

 Bolbopodium : completely enveloped by the disjointed rhombic leaf 



bases of different lengths (Saporta). 

 Cylindropodium : leaf bases short, densely crowded, with rhombic, 



convex scars (Sapoi^ta). 

 Clathropodium : leaf bases long-rhombic or elliptical in cross-section 



(Saporta). 



THE NEW GENUS CYCADELLA. 



The peculiar outer coating or second armor of the Jurassic 

 cycads of Wyoming obviously constitutes a good generic charac- 

 ter. At the same time, as is seen by the above descriptions, it is 

 wholly different from that of any other genus of cycadean 

 trunks, and it is therefore necessary to regard it as a new genus, 

 altogether different in its most essential generic characters from 

 any other. From the general small size of these trunks, espe- 



1 Buckland's description was not compact. 



