BRITISH FERNS. 49 



and attached to the rachis only by their stalk. The pinnulae 

 are roimded, and slightly crenate. Over the whole of the under 

 surface are scattered small yellowish glandular globules, which 

 are adhesive to the touch, and emit a powerful, but not very 

 agreeable odour. It is probably in consequence of this property 

 that this species has so frequently been mistaken for the Poly- 

 podium fragrans of Linneus, a plant which I consider perfectly 

 distinct, and one which has not yet been discovered in any part 

 of the United Kingdom. 



The veins in the pinnulae of Oreopteris are a simple alternate 

 series : they cease just before reaching the margin, first bearing 

 a circular and nearly naked mass of thecae ; sometimes, however, 

 the veins divide just before their extremity, and then each 

 branch usually bears a separate mass. The masses, varjdng on 

 each side from five to ten in number, form a regular and nearly 

 marginal series. In some instances, but very rarely, a small torn 

 white indusium is to be seen near the centre of each mass of 

 thecae (see the figure at page 47). This indusium is said to be 

 reniform — in other words, attached on one side, a character I have 

 never yet been able to detect. In general, the masses are 

 perfectly ^naked, even before the frond has unrolled, and the plant 

 presents every appearance of being a true Polypodium. 



