74 THE BOTANICAL MAGAZINE. [Vol. xxxn. No. 376. 



Polysiphonia fibrata Hary. 



in Hooker: Brit. Flora, II, p. 329. — Kny: Axillarknospen bei 

 Florideen, p. 102, Taf. I. fig. 10-13.— De Toni: Syll. Alg. IV, p. 

 893.— Cotton: Clare Isl. Surv., Mar. Alg., p. 99. 



(For other references and synonymes, see: De Toni, I.e.). 



It was after a long and puzzling study of numerous authentic 

 specimens of Polysiphonia that I have decided to identify our 

 specimens with the present species. If we meet such an Urceolata 

 form of Polysiphonia as this on the Atlantic or on the Mediter- 

 ranean coast we shall have nothing to hesitate in identifying 

 it to this species. The forms from our seas should never be 

 treated with such preapprehension. 



The present species is almost impossible to determine with 

 certainty when sterile. Kny gives a minute account on the 

 morphology of the plant and points out the distinctions between 

 it and P. fibrillosa, P. Brodiae, P. sertularioides, etc. A sterile 

 specimen of this, however, may also be referred to the descrip- 

 tions of various species with some excuse, such as P. pulrinata 

 J. Ag., P. havanensis Mont., P. acanthophora Kutz., P. deusta 

 J. Ac, P. rhunensis Thur., P. breviarticulata Zanard., and 

 the next-mentiond species P. ferulacea Suhr. Sharp distinctions 

 between these species, if all valid, are only possible when they 

 are either cystocarpic or tetrasporiferous. Even in the latter 

 case, P. £brata Harv. is often difficult to distinguish from P. 

 ferulacea Suhr. I take by the former species a Polysiphonia of 

 the Urceolata type with the articuli in the middle parts of frond 

 longer than 1% times of diameter and with globular or orange- 

 shaped cystocarps, or tetrasporangia unilaterally disposed in 

 the "distorted" stichidia. A further remark will be given under 

 the heading of the next species. 



An authentic specimen of P. acanthophora Kutz. in my 

 possession agrees quite well with those which I here refer to 

 this species. But J. Agardh has synonymized Kutzing's under 

 his P. sertularioides. Referring to the illustration of the plant 

 in Tab. Phyc. XIII, Taf. 76, the reduction done by J. Agardh 

 seems to me to have been based on a good ground. The 



