DICTYOTACEiE. 00 



Chorda filum. Thread Chorda. 



Frond cartilaginous, slimy, tapering from the middle to 

 each end, varying in length from a few inches to thirty or 

 even forty feet. When young, covered with slender fibres, 

 which are worn off as the plant matures ; occasionally the 

 tips of the fronds become inflated, and may be seen floating 

 above the surface of the water, but specimens in this state 

 are not common. 



Chorda lomentaria. Constricted Chorda. 



Erond a simple membranous tube, slender at the base, 

 constricted at distant intervals, so as to give it the appear- 

 ance of being pointed, tapering at the tip. 



The differences between this and the preceding species 

 are so great that some writers are doubtful whether both 

 should be included in the same genus. C. lomerdaria 

 occurs frequently on our coasts. Its fronds usually grow 

 in tufts, are thin in substance, free from slime, and are 

 not more than a foot long, frequently only a few inches. 

 I gathered specimens near Whitby, Yorkshire, of a very 

 small variety which was growing abundantly on the rocks 

 near high-water mark. The fronds were only two or 

 three inches long, not constricted, and, when growing, 

 had the appearance of tufts of stunted grass. 



Order 4. DICTYOTACEiE. 



Fronds without joints. Spores superficial, disposed in 

 definite spots or lines. 



Genus XIV. CITTLEEIA. 



Root covered with woolly fibres. Prond flat, of thickish 

 substance, expanding upwards, irregularly cleft or forked. 

 Fructification of two kinds on separate plants, dotted over 



