28 CdirMON BEAICES. 



fig. 6 ; and all the partial rachides are more or less circinate, 

 as shown in the figure at page 23. 



There is something very anomalous in the rapid development 

 of the foliaceous portion of the frond. At a stage, as regards 

 the stipes, when the circinate frond of Pteris tremula exhibits, 

 if unrolled, all its pinnae and pinnules, and even the incipient 

 fructification, that of the present species is a mere indication, 

 a slight inequality on the surface, and its component parts can- 

 not he detected under a lens of high power ; yet, in a few days, 

 we find it has increased and unfolded with such marvellous 

 rapidity, that in aquilina we have a frond surpassing in magni- 

 tude that of nearly every other British fern. 



The form of the frond is nearly triangular, the base being 

 somewhat, but not materially, the shortest of the three sides. 

 The stipes is rather more than half the length of the frond ; it 

 is green, and rather pilose : the pinnae are pinnate ; the pin- 

 nules pinnatifid ; the lobes are generally rounded and entire, 

 but sometimes again divided: the first superior pinnule on each 

 pinna is usually very small, and, as it were, rudimentary only. 



The fronds are almost invariably fertile, but all parts of the 

 same frond are not equally so. In seedling plants, or those 

 which occasionally grow in caves, fissures, or on stone walls, 

 the fronds are smaller, tender, delicate and barren ; the mar- 

 gins of the lobes of the pinnules are then flattened, and broadly 

 notched. 



Mr. Lees sent me an example of this form, gathered on a wall 

 near Worcester Cathedral ; Mr. Westcombe another, found on 

 a wall in the centre of the cit}' of Worcester : it occurs com- 

 monly on the garden-walls at Deptford, and in one instance 

 it has established itself on the brick wall of a house in that 

 town. Mr. Woodward's collection contains a fine example, 

 gathered by Mr. Pamplm at East Grinstead ; and Mr. Ewing 

 has, for many years, observed a solitary plant growing on the 

 wall of the bridge of the castle-moat, at Norwich, the fronds 

 varj'ing from three to nine inches in length. In these and 

 other instances, too numerous to mention, the same characters 

 are always preserved. 



The portion of the stipes below the ground is of a dark 

 brown colour, velvety, and considerably stouter than the por- 

 tion above ground ; and it closely resembles the rhizome in its 



