ON DASYLIRION AND BEAUCARNEA. 323 
a... what has been stated by Mohl, and described and figured by the 
Baroness von Reiche nba ch. © Acco rdin ng to Reess, the communication 
between the * thylle" and the mother cell persists for some time, the 
ab 
to be the acing up of starch, which appears to me a somewhat doubtful 
hypothesis. Besides the plants already enumerated, “ thyllen” have 
n observed in Quercus, Platanus, and Robinia. The earliest repre- 
sentation of them is given by Malpighi (1686), in his “ Anatome Plan- 
" (vol 1, tab. 6), from the oak. His remark about them is 
« fstule frequents pulmonares quasi vesiculas trachearum substantia ex 
citatas continent” (p. 9). 
eess enumerates a number of writers who have discussed Tyloses ; to 
these E be added eee Das Mikroskop., p. uis and Sachs, who 
b ntis a non-gymnospermous exogenous wood from the lias, 
i Mr 
in pass ing, that ma paper of Mr. Sorby's appears to have escaped the 
Presuming the id osed geological horizon to be beyond dispute, this 
P a ei the oldest known fragment of an angiospermous 
nerogam 
have prefixed the term Tyloses to. this article. Professor Van 
Heurck defines them to be “ cells formed by wood parenchyma o r by 
medullary rays which penetrate into the vessels through the punctation 
(‘ Le Microscope,’ 2nd. ed. 1869, p. 157). In the ‘ Geological Magazine,’ 
me by a false analogy to words like "' cellulose," I used the term 
erroneously in a collective sense, in the singular form, and it appears so 
consequently upon the plate. . 
ExrrawATION or Pirate CXXVI. 
(Kindly lent by Mr. H. Woodward from the ‘Geological Magazine.) 
Fic. 1. Transverse and ndicular section of a wedge of the 
fossil eocene wood. from Ep die of hanet, showing ducts containing tyloses, 
spe 
sam 
es. " E " 
ocene wood to show arrangement and character of pores. Fig. 5. Tex. 
and Fig. 6, perpendicular section of the wood of the vine showing awe filled 
daos tyloses; porous wood-parenchyma is shown on the right of Fig. 6. 
ON DASYLIRION AND BEAUCARNEA. 
By J. G. Baxer, F.L.S. 
(Oontinued from page 299.) 
- BEAUCARNEA, Lemaire, Ill. — tome viii. Mise. p. 59 cum tcone. 
Pi incenictitia vel Puscnie; Hortoru ulinia, 4 r^s Joc a ex 
Bor- 
e. Dasylirion, Zuce. et. Kunth, ex "in Yucce sp., 
dylinis sp» H.B.K. et Benth. ig end polygamo-dioici : e Perian- 
