Marine Alga j of Berwick-on-Tweed. 231 



Bab. Epiphytic on Gafenella Opuntia, Laurencia pinnatifida, and other 

 small Algae. Fruit Jan. and Feb. Not uncommon. Berwick 

 Bay, Burnmonth, Holy Island. 



A small epiphytic species composed of a number of 

 shaped cells radiating- from the base, united into hemispherical 

 green masses. When in fruit the cells are entirely filled with the 

 numerous round green spores. With us the plant is in fruit from 

 December to February. 



A narrow form of this species epiphytic) on Laurencia pinnati- 

 fida, occurs at Sharper Head. It comes very near, if it is not 

 identical with, Sphcenosiphon (Dermocarpa) incrustans, Reinsch. 



Dermocarpa Schousboet, (Thur.) Hornet in Hit. 



Xenococcus Schousboei, Thur., Notes Algol, n. p. 73. 



Descr. Xenococcus Schousboei, Thin-., I.e. 



Figs. „ „ Thin:, I.e. pi. 26, fig. 1-2 (Tab. Nost. VII. 



tig. 2b. 

 Exsicc. Dermocarpa Bchousboei, Holmes, Alg. Brit. Ear. Exsicc, no. 80. 

 Hab. Epiphytic on Rhodochorton Rothii, and other small Algae, in 



shallow paddles near high water mark, often in company 



with B. prasina. Fruit Jan. — Feb. Rare. Berwick Bay. 



Sharper Head. 



The genus Xenococcus was founded by the late M. Thuret on 

 barren specimens of this plant collected by Schousboe in Tangier 

 in 1825, but no form of fructification was known till the spring 

 of 1887, when I detected the spores on specimens which I had 

 collected at Berwick in January of that year. The fertile 

 cellules are globose and sessile, and contain a large number of 

 nearly round spores. It still remains to be proved whether the 

 spores escape from the mother cell by the circular rupture, or 

 by the dissolution of the membrane. Dr. Bornet, to whom I am 

 indebted for the identification of this and the preceding species, 

 has pointed out that this discovery of the fructification renders 

 the retention of the genus Xenococcus unnecessary. 



The species is distinguished at sight from Dermocarpa prasina 

 by its nearly spherical cells, the cells of the latter species being 

 wedge-shaped and radiating from the base. 



Note. — Several species of Schizomycetes belonging to the genera 

 Beggiatoa, Leptotlirid\ and Colini/i (Clathrocystis) are not uncommon at 

 Berwick during the summer and autumn on mud and decaying Algae.. 



