(118) 



olive. Fructification : obovate spores produced at the bases of the 

 filaments of the periphery. 



This curious species is common on all our shores between tides, both 

 on the sides of rocks and in the rock-pools, and, as far as we have been 

 able to ascertain, is generally parasitical on the smaller Algse, preferring 

 Laurencia pinnatifida, Corallina officinalis, Ceramium ruhrum, &c. When 

 growing on the last-named plant they are mostly small, seldom much 

 larger than peas, and generally quite roimd, but when gi^owing on the 

 stunted varieties of Laurencia -[minatijida it is often of large size, and 

 the shape very in-egular, especially when old : then- size also varies from 

 that of a small pea to that of one or two inches. In Scotland it is in 

 perfection in July and August, after which it soon disappears. Its 

 curious structure forms an interesting object, under the microscope, from 

 the variety and singular forms of the cells. Externally the plant has 

 no great beauty, but that is amply compensated by its curious micro- 

 scopical structure. 



% ,9 f 



LEATHESIA TUBERIFORMIS. 



Fig. 1 



EXPLANATION OF DISSECTIONS, &c. 

 -Fronds of Leatliemi tuheriformis, natural size. 



Portion of a longitudinal slice showing the dense coloured 

 outer wall and the fibres. 

 3. — Apices of the fibres with club-shaped filaments. 

 4. — The same with spores. All magnified. 



