66 Brady^ on the Seed of Dictyoloma Peruviana, 



render the rest of my paper more intelligible^ I may be 

 allowed to advert to it in a few words. 



When mature, it is a roundish or kidney-shaped seed, about 

 a quarter of an inch in diameter, thickest at the centre, and 

 gradually thinner towards the outer edge, which we find ex- 

 panded into a thin, membranous wing (PI. VII, fig. 5). 

 Careful examination shows that the cells on the outer layer 

 of the testa, which appear on the body of the seed in the 

 form of irregular projections, are, towards the circumference, 

 excessively developed, especially in length, and it is in this 

 way that the expansion alluded to is formed. The side walls 

 of these elongated cells become much thickened in the 

 process of growth, thus affording to the wing the necessary 

 strength and firmness, whilst the front and back walls retain 

 their original transparency, being marked only by a very 

 delicate subspiral deposit. A glance at the accompanying 

 sketch (fig. 6) will supply any deficiencies of this verbal 

 description. 



This introduction will, I trust, render intelligible the more 

 complicated structure which is observable in Dictyoloma 

 Peruviana. A general idea of this beautiful seed may be 

 gathered from fig. 1. Endlicher's description of it, which 

 is very defective and partially incorrect, runs thus : — " Semina 

 late reniformia, compressa, dorso in alas duas parallelas 

 radiatim reticulatas, fibra marginali connewas expansa, sinu 

 ventrali umbilicata." As we may infer from the above, 

 it is broad, kidney-shaped, and flattened. Besides possessing 

 a wing formed in a similar manner to that of Eccremocarpus, 

 by the expansion of the testa round the edge, there are 

 several succesively smaller, lateral wings in the same plane, 

 the margins of which form a series of concentric rings over 

 either surface of the seed. These smaller wings lie close to 

 the surface, and appear almost like a continuous coat of 

 connected cells ; indeed, those nearest the centre seem to be 

 more or less connected through their entire length to the 

 seed itself, the outer extremities only being raised above 

 the general surface, thus keeping up the appearance of con- 

 centric rings above alluded to. The alae, as they approach 

 the circumference, become successively larger, and to a 

 greater extent free. The sectional sketch, fig. 2, represents, 

 as nearly as I can make out from the small materials at my 

 command, the arrangement of the wings. 



But perhaps the structure of the alse themselves is the 

 most remarkable feature in the case. Each wing appears to 

 consist of a series of radiating fibres connected at their outer 

 margin, the spaces between them being left quite open. 



