I MR. W. C. WILLIAMSON ON THE HISTORY OF ZAMIA GIGAS. 



on the Yorkshire coast, whilst the invaluable and suggestive assistance of M. Adolphe 

 Broagniart has always been available whenever specimens were submitted to his inspec- 

 tion. Would that I could personally thank three other geologists, whose cabinets were 

 iivrly thrown opm to me; but Dr. Murray and Mr. Bean, of Scarborough, and Mr. 

 Ripley, of Whitby, have passed beyond the reach of earthly thanks since most of the 

 preceding pages were written. 



EXPLANATION OF THE PLATES. 



Plate LII. 



Pig, 1. Cast of the superior surface of the "carpellary disk/' 

 Y\+. 2. Cast of the inferior surface of ditto. 



Pig. 3. Inferior aspect of an involucrum, showing the cylinder of vascular tissue within the pyriform 



axi^ 



Pig. 4. Longitudinal section of an involucrum, with the pyriform axis and the inferior half of the lenti- 

 cular disk. 



Pig. 5. Upper portion of an involucrum, with the impression of the inferior surface of the lenticular 



disk. 



Pig. 6. Basal aspect of a matured involucrum, in which the central portion has been broken away, 



revealing the interior of the pyriform axis. 

 Fig. 7. Basal aspect of a young involucrum. 



Plate LIIL 



Pig. 1 . Restoration of the male plant of Zamia Gigas. 



2. Restoration of half of the carpellary disk, showing the vascular exterior, tfc 



chyma, the ovules in situ, and the position of the supposed abortive ovules. 

 Pig. 3. One of the rays of fig. 1, Plate LII.; double natural size. 

 Pig. 4. Ditto, with seeds in position; restored. 

 Pig. 5. Impression of a portion of the exterior of the stem. 

 Fig. 6. Upper part of the pyriform axis with the pyramidal axis and corona. 

 Fig. 7. The pyramidal axis and corona. 

 Fig. 8. Ditto, ditto. 



Fig. 9. Section of immature lenticular disk and corona. 



« * - — _ - 



I g. 11. Longitudinal section of ditto. 



pyn 



- 



ucrum 



! - ! '». Restored section of ditto. 

 Hg. 1 1. Seed; nat. size. 

 Pig. 15. Seed: enlarged. 



.Vote '.-Since writing the above Memoir, Mr. Leckenby's cabinet has afforded me proofs 

 ^ r *'" f 6Cten WQS a ****»*■ He has both forms of fructification. A 



a 7LI « V i ^ Sh ° WS that tUs S P ecies sl ' 01lld als ° be referred here. I hav, 



5 It '' lC " X ?' ma ^ ° f el0n § ated cells of th « "-shaped base of the len- 



n ! o .t T Ut * mCh ln thk ' W > and that * i»er surface .as as sharply defined 





