LASTREA. 127 



which are separate from each other. The pinnae are narrow 

 and tapering, with a few of the lowest pinnules distinct, the 

 rest united at the base ; these pinnules are of an obtusely 

 oblong form, and serrated on the margin. The fructification 

 of this plant is generally very copious, and is usually con- 

 fined to the lower half of the pinnules, where it is crowded. 



This is one of the best species to study with the view of 

 understanding the fructification of Ferns, for here the indu- 

 sium, a very important organ, is seen to be remarkably pro- 

 minent in fronds which have about reached their full deve- 

 opment. In that state the indusium is as yet closed over 

 the clusters of spore-cases, and will be seen to consist of a 

 lead -coloured, tumid, kidney -shaped, conspicuous scale, 

 which, at the proper time, becomes elevated on one side to 

 allow the dispersion of the spores. This may readily be seen 

 by closely watching the progress of the fronds after they 

 have reached the stage just adverted to; or if they are 

 gathered in that state for preservation in the herbarium they 

 are almost certain to burst, more or less, in the process of 

 drying, before they yield up their vitality. These covers are 

 at first little white scales. 



The veins of this species are also readily seen, and each 

 pinnule will be found to have a flexuous midvein, with 



