462 MISS T. L. PRANKERD ON THE STRUCTURE OF 
only, i.e. L. Sinclairi and L. Kidstoni, though the latter has much in common 
with Physostoma (14, p. 112). 
Since Williamson’s original deseription many other specimens of Lageno- 
stoma ovoides have come to light, and some preparations have been partially 
described and figured by several writers (Chodat (5), Coulter (6), Benson (2)). 
The following account is based mainly on the collection handed те by 
Professor Oliver, of the Botanical Department, University College, London. 
This consists of preparations (numbered В. 20- R. 56 *) from forty whole seeds 
and from four imperfect specimens. Two preparations have been made from 
the same seed in four cases, but there is unfortunately no series of three 
sections from the same seed—often of more value than a dozen sections from 
different seeds. This material was supplemented by the eleven specimens 
of the Williamson Collection in the Geological Department of the British 
Museum at South Kensington, which I was enabled to examine by the 
courtesy of Dr. Smith Woodward, F.R.S., and also by a few other prepa- 
rations which are acknowledged when reference is made to them. 
II. GENERAL DESCRIPTION. 
A. External. 
As its name implies, the seed is egg-shaped, tapering slightly towards the 
apex, and broadest about the middle. Williamson gave 016 x 0*1 (inch) for 
the dimensions, which were probably somewhat greater (about 4:5 x 3 mm.), 
as he had not sufficient material to construet an entirely median section. 
Good transverse sections are not, strictly speaking, quite circular in 
outline, but obscurely polygonal (usually octagonal) (PI. 28. fig. 16), showing 
that the seed was slightly angled, the angles dying out a very short distance 
from the micropylar orifice. Radiating from the latter are a crown of tiny 
ridges, about 600 ш in length, and equal in number to, though much more 
prominent than, the angles, with whose direction they alternated. The ridges 
and angles died out at about the same level. The truncate base is rather 
more than a millimetre in diameter, and shows a very slightly prominent 
rim and a central papilla. There is very little trace of a layer of separa- 
tion, and though, from analogy with Layenostoma Готаги, а cupule was 
to be expected, no trace of any such organ has been recognized, though 
Jhodat figures, without describing, what he terms the “arile charnu ” 
(5, pp. 27 & 28). 
* When more than one seed occurs on the same slide,it is referred to by a figure in 
brackets after the number of the slide, reading from left to right, and from above to below. 
Thus В. 48 (3) means the lower left-hand specimen of the four seeds which occur on this 
slide. 
