140 BRITISH SEA-WEEDS. 



Nitophyllum punctatum. The dotted Nito- 

 phyllum. 



Fronds growing in tufts from a small disc-root, from four 

 to twenty inches long, and nearly as broad, oblong, delicately 

 thin, destitute of veins, either regularly divided or cleft into 

 two or three principal segments, fringed at the edge with 

 dichotomous lobules. Spores contained in large hemisphe- 

 rical conceptacles, which are thickly scattered over the 

 whole frond ; tetraspores tripartite, grouped in large, dark 

 red, oblong spots. 



The above description applies strictly to the normal, 

 or typical, state of the species. In the 'Phycologia 

 Britannica,' Dr. Harvey has described three varieties, 

 which, though differing from each other very considerably 

 in form and general appearance, are not sufficiently dis- 

 tinct to be separated into species. The first variety 

 j8. ocellatum is divided to the base into linear, dichoto- 

 mous lobes, with a perfectly even flat margin. In 7, 

 crispatum the frond is thicker and of a darker colour, from 

 half an inch to an inch broad, and from six to eight inches 

 long, dichotomously divided, and strongly curled at the 

 margin. Variety 8. Pollexfenii is also thicker than the 

 typical form, wedge-shaped at base, variously lobed, and 

 has a rounded margin. Variety e. fimbriaium is very 

 thin, without fruit, roundish, the margin cut into minute 

 forked lobes about a line in breadth. There are other 

 less distinct varieties intermediate between all of these, 

 which gradually connect the extreme broad and narrow 

 forms in one unbroken series, and clearly prove that all 

 belong to the same species, altered only by varying cir- 

 cumstances of growth. Nitophyllum punctatum is found 

 on many parts of the English coast, but nowhere in 

 great abundance, and very seldom of a large size. The 



