FLORA OF THE SHASTA FORMATION. 247 



with reference to the midrib. Those lowest down stand at a large angle; 

 it may be a right angle. The nearer you approach the end of the leaf 

 the more oblique are the leaflets, and at the end they stand in the pro- 

 longation of the midrib. I regard the mode of attachment of the leaflets 

 to the midrib as the most important, and it certainly is the most 

 unvarying, feature of this plant. The leaflets are attached, not on the 

 face of the midrib, but to the side in the plane of its upper face. The 

 epidermis of the leaflet is continuous with that of the midrib. So far 

 are the leaflets from being articulated with the midrib that they are 

 remarkably persistent. They are narrowed toivard their bases, but not 

 at them, and there is no abrupt rounding off at the base as in Zamites, 

 but they are decurrent along the midrib. The terminal leaflets ai'e 

 always decidedly narrower than those lower down on the midrib and, 

 as before stated, are much more obliquel^y placed. 



Nathorst, in describing specimens of this species obtained from 

 Japan, has proposed Zamiophyllum as the generic name for it." He 

 objects to the name Dioonites for this plant because it is unlike Dion in 

 having its leaflets narrowed toward the base and in having them obliquely 

 placed. He states further that he thinks it not impossible that the 

 plant now in question may belong to the living genus Zamia. The first 

 objection is the only one that holds good, for, as has been stated, the 

 second is not applicable to the leaflets in the lower portion of the leaf, 

 and, in any case, such a feature can have no great value. Perhaps it 

 would have been better in the original determination of the plant to have 

 placed it in a new genus, but it does not seem fitting to rename it with 

 such a generic appellation as Zamiophyllum. This suggests an affinity 

 with Zamia, of which there is no evidence. It differs from Zamia in the 

 absence of articulation of the leaflets and in their marked persistence on 

 the midrib. Besides, the basal portions of the leaflets differ in form 

 from those of Zamia. Seward, as before stated, describes a number of 

 fine forms that he identifies with Dioonites Buchianus." He includes 

 these plants in the genus Zamites, modifying the generic description 

 somewhat. His figures and descriptions make it plain that his fossils 

 are different from the Potomac forms described bj^ me as Dioonites 



« Beitriige zur Mesozoischen Flora Japans, pp. 6, 7 (see synonymy, p. 245). 

 b Fossil Plants of the Wealden, Part II, pp. 75-86. 



