WILLIAMSONIA. 189 1 



structure has also been figured by Saporta as " unc expansion 

 infundibuliforme." l 



The disc was originally circular, as we know from other 

 specimens, the centre being shown at the base of the figure in 

 PI. VIII. As seen in surface- view, the disc has the form of 

 a cup-shaped, irregularly striated, carbonaceous membrane, breaking 

 up at the periphery into several long and tapering bracts. The 

 continuous portion of the disc has a diameter of 8-5 cm. It is 

 probable that this organ was originally attached to the summit 

 of a Williamson ia flower, but we have no satisfactory evidence 

 as to its function. 2 Portions of fronds occur on the same piece 

 of rock as the disc shown in Fig. 1 , PI. VIII. 



Oolitic Ironstone, Saltwick. Sean Coll. 



V. 2507. Imperfect flowers, in which the scale-leaves show 

 the irregular and occasionally anastomosing ridges, which are no- 

 doubt due to the presence of strands of hypodermal stereome. 



Purchased. 



V. 2887. Basal view of flowers, showing bracts and rainenta. 



V. 2887. A peduncle, 1 8 cm. long, covered with imperfect 

 scale-leaves and terminating in a bud enclosed by scale-leaves 

 identical with the involucral bracts of the detached flowers. 

 Numerous pinnae occur on the same piece of rock. 



Near Scarborough. Beckles Coll. 



V. 3512. Similar to V. 2887, with short and broad involucral 

 bracts. 



13,512. The impression of a disc with peripheral bracts, similar 

 to the example shown in PI. VIII. Fig. 1 (38,785). 



Haiburn Wyke. Presented by Dr. Murray. 



Other specimens: V. 2609, V. 3513 (fragments of flowers and 

 fronds), 39,087, 39,094, 39,304, 40,556, 52,559. 



1 Saporta (75), p. 148. 



2 Vide Seward (95), pp. 152, 153. 



