Greville^ on Neiv Diato7ns. 
67 
Fig. 3 represents a portion of the outer sets of wings under 
a higher magnifying power, and this sketch will also serve 
to show their position with regard to each other. I was 
some time before I could satisfactorily account for this 
singular character, and it is only after a number of obser- 
vations on other winged seeds bearing more or less on my 
specimen that I am enabled to speak with confidence about 
it. The separate wings seem to be formed in the manner I 
have just described in reference to Eccremocarpus. The 
cells of the outer layer of the testa are developed to a great 
length, and the side walls are thickened in the same way ; 
but the front and back walls, not being supported by 
deposit of any sort, are ruptured at a very early stage, and 
gradually disappear, leaving the side walls only as a sort of 
framework or skeleton. The frequent raggedness of the 
sides of the fibres is best accounted for in this way, and the 
appearance of one of the inner wings carefully removed from 
the seed (fig. 4) fully confirms this view, as it still retains 
portions of the delicate cell-wall only partially disintegrated. 
I had hoped that an examination of the ovules in a very 
early stage would have shown the outer wings entire, but in 
the only flower which I have had an opportunity of dissecting 
the ovary was too immature to throw any light on the 
subject. Altogether, the specimen I have described reminds 
one strongly of the leaf of Ouvirandra fenestralis, and 
though botanically the phenomena are not. identical, it loses 
nothing in interest by such association. 
In conclusion, I must acknowledge my thanks to my 
friend. Professor Oliver, for the specimen from which this 
notice is written, and Mr. Tuffen "West for memoranda from 
seeds in his own collection bearing somewhat on the present 
case. 
Descriptions of New and Rare Diatoms. Series II. 
By R. K. Greville, LL.D., F.R.S.E., &c. 
(Read June 12th, 1861.) 
Rylandsia, n. gen., Grev. and Ralfs. 
Frustule simple, disciform, cellulose; disc with smooth 
rays, dilated at their base, and not reaching the centre. (No 
umbilical lines nor hyaline area.) 
