G. R. Wielcmd-— Williamsonian Tribe. 459 



Almost at the same time this far southern Williamsonian 

 flora was discovered, Nathorst and Halle had been at work on 

 the Yorkshire coast, and there too, fully demonstrated that all 

 ideas of a paucity of Williamsonian ovulate fruits in either 

 number or variety of species have been due to almost unac- 

 countable failure of botanists and paleobotanists to engage in 

 adequate field work. Nathorst had indeed found at Cloughton 

 Wyke the first type of his Williamsonia LeckenJnji thirty 

 years ago (9); but it is only this later work that has demon- 

 strated the presence of variety of species. 



In some cases it appears that the strobili had an outer form 

 much like a Nelumbium fruit (25, p. 25), but the writer, while 

 finding in the Mixteca Alta forms he at first explained in the 

 same way, wonders if splitting away of an outer surface as the 

 only part conserved, after the manner shown in figure 14i? 2 , 

 may not throw some light on the Nathorst fruit. 



In summation then, it may be said that at the present time 

 it is likely that to the score or so of species of ovulate cones of 

 the Cycadeoidese may be added about an equal number of 

 species of Williamsonian strobili, mainly from the Yorkshire 

 coast, India and Oaxaca. But while much variation in size 

 has been noted, hypothetic or reduced few-seeded forms, or 

 types of lax structure, have not yet been determined ; so that 

 the range of ovulate structure approaches but does not so far 

 equal that seen in the Coniferales. The reverse is true when 

 staminate structures are also brought into such a merely gen- 

 eral comparison. 



Staminate Fructification. (Figures 16-18.) 



It has been justly doubted by Professor Nathorst, to whom 

 we owe the demonstration of the type-series of staminate 

 Williamsonia fruits from the Yorkshire coast, if the nature 

 of these pollen-bearing structures could ever have been satis- 

 factorily deciphered before the elaboration of the silicified 

 bisporangiate strobili of Cycadeoidea. For not only are the 

 essential structures of the imprints of staminate organs difficult 

 of observation, but the exigencies of preservation are greater 

 by far than in the case of the ovulate cones. Indeed, because 

 of the compact and durable form of the latter, with a require- 

 ment of several years for reaching maturity and shedding of 

 the seeds, it might well be expected that many examples must 

 be found to one of the fragile staminate fruits of quicker 

 growth, probably as a rule dehiscent only after the wilting 

 down of their little resistant tissues. Yet, evidence of stami- 

 nate fructification has been accumulated with fair success, and 

 now that the outlines of the disks in a number of species and 



