(32) 



the base, the margins all more or less ciliated with minute subulate 

 teeth, which when young are furnished with tufts of very delicate 

 byssoid filaments. 



This beautiful species is said to be not uncommon on all our shores. 

 We have not met with it on the Forfarshire coast, although it is given 

 in a list of Forfarshire Algae, by Mr. Don. 



The species of the genus Desmarestia differ so widely at different 

 stages of their growth, that no one who has not traced them through 

 their various stages would suppose for a moment that the rough, harsh, 

 wiry-looking plants of autumn were identical with the beautifully light 

 and delicate feathery-like fronds of early summer — so tender and delicate 

 that they yield to the least movement in the water, forming the most 

 graceful and beautiful curves as they rise and fall with the heaving 

 swell. 



Under the present species we would place the form D. pinnatinervia, 

 our impression being that they are identical ; although at first sight 

 the great breadth of the frond, and the very narrow and distinct 

 pinnated nerve, would indicate a distinct species. 



We have not seen the variety in its native haunts, nor have we 

 seen either of the fonns in the young state. We have specimens of 

 D. pinnatinervia collected in the north of Ireland from various coitc- 

 spondents, but are not aware if it has been met with elsewhere. 



EXPLANATION OF PLATE CXLIL 



Fig. 1. — Desmarestia ligulata, natural size, 

 2. — Pinna, narrow variety. 

 3. — Pinna, broad variety. 

 4. — Transverse section of stem. All magnified. 



