in which it may grow ; but, on a careful examination of numerous 

 specimens of these varieties now before me, I cannot fix on any 

 characters which appear of specific value. My friend Mr. Hore 

 finds that the utricles or spores of the small variety which com- 

 monly grows on Besmarestia aculeata are borne on little stalks, 

 while in the common form represented in our plate they are 

 mostly sessile ; and this character, were it constant, would afford 

 a readily appreciable mark of distinction. But when making 

 the sketch for the magnified ramulus (fig. 4) taken, without 

 selection, from a specimen of the common form, I observed that 

 though the spores are often nearly sessile, there is frequently a 

 short pedicel. And when any disposition to form a pedicel exists 

 in so variable a plant as this, its amount must be most uncer- 

 tain. The spore is to be regarded morphologically as an abbre- 

 viated ramulus ; where the whole ramulus is converted into a 

 spore, that organ will be sessile ; but when a part only is so 

 changed, it will be stalked. 



This species was once confounded with S. plmnosa, but differs 

 from that beautiful plant in habit and size, in its jointed main 

 filaments, and in being far less regularly pectinato-pinnated, 

 with proportionally shorter pinnules. Being a very common 

 plant, it was among the first of the genus observed by botanists, 

 and is figured in the Historia Muscorum of Dillenius, under the 

 specific name here preserved. By Hudson it was subsequently 

 called pennata, a name adopted by succeeding authors until the 

 older one was restored by Roth. 



Fig. 1. Sphacelaria cirrhosa; tufts: — of the natural she. 2. Part of the 

 stein and pinnated branches. 3. Apex of a branch with ramuli. 4. 

 Hamulus with utricles. 



