Marine Algce of Berwick-on-Tweed. 289 



Ealfsia spongiocarpa, Batters. 



Journ. Linn. Soe. Bot., vol. xxiv., p. 457, pi. 18,* fig. 17-21. 



Exsicc. Ralfsia spongiocarpa, Holmes, Alg. Brit. Rar., no. 91. 



Hab. On the rocky bottoms of shallow pools half filled with sand, near 

 low-water mark. Fruit Jan. and Feb. Rare. Berwick Bay. 



Smaller and thinner, and retaining its orbicular form for a 

 longer time than Ealfsia clavata, which it closely resembles to 

 the naked eye. The paraphyses, however, are cylindrical or 

 slightly attenuated to the apices, never club-shaped. They are 

 composed of from 10 to 12 cells, if any thing rather broader than 

 long below. The sporangia are smaller than those of Ealfsia 

 clavata, and more oval in shape, sometimes even nearly globular, 

 and although usually lateral at the base of the paraphyses, one 

 not unfrequently finds them terminal as in the genus Lithoderma. 

 The filaments composing the frond are occasionally more or less 

 forked. 



Altogether the plant reminds one of Wollny's description of 

 his Lithoderma maculiforme,] which however is a true Lithoderma 

 the unilocular sporangia being always terminal and not ac- 

 companied by paraphyses. It is also a much smaller plant than 

 my Ealfsia spongiocarpa being little more than a mere speck. 



I have found what appear to be plurilocular sporangia both in 

 Ralfsia clavata and Ealfsia spongiocarpa. They form indefinite 

 sori on the surface of the frond, and are composed of cells placed 

 end on end so as to form filaments, the upper cells of which seem 

 to contain zoospores. Except that they are a little less in diameter 

 they much resemble the vertical filaments of the thallus, and I 

 feel far from certain what their real function may be. 



Family— ]YI yrionemateae. 



MYRIONEMA, Grev. 



Myrionema vulgare, Thur. 



in Le Jol., Liste des Alg. Mar. Cherb., p. 82. 

 Descr. Myrionema vulgare, Farlow, Mar. Alg. New Eng., p. 79. 

 Fig. Myrionema strangulans, Harv., Phyc. Brit., pi. 280. 

 Si/n. Myrionema strangulans, Grev., Crypt. Fl., t. 300 ; J. G. Ag., Spec. 

 Alg. i., p. 48; Ktz., Spec. Alg., p. 540. 



*The Linnean Society have kindly permitted this plate to be reprinted 

 to illustrate the present paper (it is now plate vm.) 

 t Hedwigia, vol. xx., p. 31, PL n., fig. 1-4. 

 1 L 



