142 BRITISH SEA-WEEDS. 



scattered over the frond; tetraspores oblong or roundish, 

 abundantly scattered over the frond. 



Like the other species of this genus, Nit ophy Hum Bonne- 

 maisonii varies very much in form. Some fronds are 

 cleft nearly to the base, others are scarcely divided at 

 all ; some are entire, and some proliferous at the margin. 

 It grows in deep water, and is sometimes cast on shore 

 on the stems of Laminaria digitata. 



Nitophyllum Gmelini. Gmelin's Nitophyllum. 



Frond from two to six inches high, expanding from a 

 short stalk, which springs from a small disc-root, m ore o r 

 less deeply cleft into waved lobes ; veins at the base of the 

 frond distinct, gradually becoming fainter upwards. Spores 

 in hemispherical, depressed conceptacles, which are generally 

 formed near the margin of the frond, or in the upper lobes ; 

 tetraspores always placed just within the margin of the 

 frond. 



This species grows on rocks and large sea-weeds, at 

 and beyond low-water mark. It is in perfection in sum- 

 mer, and occurs most frequently on the south coast of 

 England, the west of Ireland, and the Channel Islands. 

 It may be known by its marginal tetraspores, and pecu- 

 liar crisp texture. 



Nitophyllum laceratum. The jagged Nitophyllum. 



Fronds four to six or eight inches long, dichotomously 

 divided, sessile, or having a very short stalk with a disc-root, 

 which sometimes throws out creeping fibres ; the lobes are 

 of a thin delicate substance, linear or wedge-shaped, with a 

 curled or dentated margin ; the basal veins are distinctly 



