G. R. Wieland — American Fossil Cyeads. 223 



regularly distributed in the same relative position, they are in 

 some way connected with the floral plan, though not likely as 

 essential organs. 



In figure 2. which is a diagrammatic sketch of the transverse 

 section through the middle of the soriferal axis, based on the 

 photograph shown in Plate IY, figure 1, the plan of the flower 

 is clearly shown. There is first a series of imbricating bracts, 

 the thickly-set hairs of which are not indicated in the sketch. 

 These are in cross section quite thin and scalelike in the 

 middle and upper region of the soriferal axis, especially the 

 interior series. A cross section of the bracts near their origin 

 is seen in Plate IY, figure 2, which represents a section through 

 the base of the flower, about 2 mm below the basal sori. At 

 this height, the cross section of the bracts is approximately of 

 the same form as that of the petioles of the trunk itself. 



Inside the involucre of bracts, figure 2, 6, is the fleshy integu- 

 ment surrounding the cross area of soral distribution, which is 

 approximately that of a twelve-rayed star, with short points 

 and a hollow center. This is a second clear indication that 

 there is a general plan of twelve, the radial lines of the summit 

 previously mentioned being the first. The sori tend strongly 

 to arrange themselves in tandem pairs parallel to the sides of 

 the twelve points, thus forming an approximation to twelve 

 radial series of from four to six parallel Y-shaped groups. 

 Only the examination of a series of successive thin sections 

 now being made will show how far the soriferal surfaces are 

 barren or depart from this arrangement. 



It is obvious that the fleshy outer wall extends inward as 

 a homogeneous tissue to form most, if not all, of the soriferal 

 surface. Whether or not these surfaces had any connection 

 with a central axis is obscured by the presence of the central 

 cavity mentioned above. There does not, however, seem to 

 have been any such connection. That there is in any case a 

 series of surfaces which must be regarded as the homologues 

 of sporophylls is a point on which botanists will doubtless agree. 

 The discoveries of Ikeno' 23 and Webber, 17 and the investigations 

 of Lang, 21 do not leave any doubt as to the correct terminology 

 of Cycadean inflorescence. 



The finer structure of these organs must be treated at 

 another time, though it should be explained now that the sori 

 are composed of from twenty to forty clavate sporangia. Each 

 sporangium is about 1 mm in length and T \ mm in diameter, 

 and contains 500 or more rounded or subangular bodies not yet 

 completely studied, but undoubtedly the spores or pollen grains. 



With regard to the homology of these structures, several 

 facts are worthy of mention. The radial divisions occurring 



