( 194 ) 



strata ; filaments slender, cylindrical, sparingly branched upwards ; 

 branches cylindrical, very erect, with acute axils and obtuse rounded 

 apices. Articulations short, about once and a-half or twice as long as 

 broad, and of nearly equal diameter throughout. Substance tender, 

 rather flaccid, and adhering to the paper in drying. Colour-, a fine deep 

 pinky or purplish red. Favellse unknown. Tetraspores common, pro- 

 duced on short subterminal ramuli, in little subcorymbose clusters. 



This minute species is very common on most of oiu* shores, extending 

 its local range even to the utmost limit of high water, and generally 

 forms minute tufts or rather spots on the surface of the rock, more 

 conspicuous from their brighter coloiu- than by their size. These often 

 become confluent, and eventually form more or less extensive strata ; 

 but the filaments are generally too short to permit of their being removed 

 from the rock, except in the form of a fibrous looking powder. The 

 more dwarfish specimens near high-water mark are those most frequently 

 fruited. 



Its favourite habitat is the shady side of rocks and stones, under 

 arches, &c., where it can be sheltered from the noon-day sun, and in 

 such localities the eye of the careful collector will seldom fail in finding 

 our little favourite in greater or less abundance, and when well fruited, 

 a more interesting microscopic object can scarcely be selected. 



We follow Dr. Harvey in uniting the old " Byssus purpurea'' to this 

 species as a variety, being firmly persuaded after careful examination this 

 is its proper place. 



CALLITHAMNION ROTHII. 



EXPLANATION OF DISSECTIONS, &c. 



Fig. l.—CaUithamnion Rothii, natural size. 

 2. — Filaments. 

 3. — Tufts of tetraspores. 

 4. — A tetraspore. AU magnified. 



