12 THE MARINE ALG^ OF ESSEX. 



Laminariacese, Ag. 

 LAMINARIA, Lamour. 

 Laminaria saccharina, Lamour, "Ess./' p. 22. Harwich, 

 G. P. Hope ; Blackwater estuary, E. M. Holmes ; Clacton, E. M. 

 Holmes and E. A. B. ; Felixstowe, G. Massee. A curious form of 

 this species is found at Clacton, and was plentifully strewn on the 

 beach in January, 1893. The frond, instead of being more or less 

 rugose and bullated in the centre with undulate or curled margins, 

 is perfectly flat and even, like that of L. digitafa, and the fructifica- 

 tion forms an uninterrupted band down the centre of it. I have not 

 seen similar specimens from the South of England, but have 

 gathered the same variety near Berwick. Prof J. G. Agardh, to 

 whom I sent Berwick specimens, thought the plant might belong to 

 a new species, but it seems to me preferable to regard it, at least for 

 the present, as a variety of L. saccharina. The Clacton plants grow 

 to a length of several feet, but are seldom more than two inches 

 wide, several specimens in my possession being hardly more than one 

 inch wide, although when entire they were two or three feet long, 

 and bear mature sori. No other species of Laminaria has been re- 

 ported to occur on the Essex coast, and the species of the genus are 

 too conspicuous objects to be overlooked by collectors. 



Cutleriaceae, Thur. 

 CUTLERIA, Grev. 

 Cutleria multifida, Czrev., " Alg. Brit.," p. 60. Asexual 

 form on cement stone rock, Felixstowe ; sexual form washed ashore, 

 Harwich, G. P. Hope. The sexual and asexual plants of this genus 

 are so different in outward form that they have usually been regarded 

 by botanists as belonging to two separate and totally independent 

 genera, the former being named Cutleria multifida, the latter 

 Aglaozonia reptans. As a result of M. Falkenberg's researches into 

 the development of the Cutleriaccc, it has been proved that the oospore 

 of these algas does not at once reproduce a Cutleria, but a hetero- 

 morphous thallus in no way distinguishable from an Aglaozonia. The 

 Zonaria parvula of Harvey's " Phycologia Britannica," and the 

 Aglaozonia reptans of more modern works on British seaweeds, is 

 nothing more than the asexual form of Cutleria multifida. The true 

 Zonaria parvula of Greville, however, appears to be a really inde- 

 pendent species, which produces tetraspores very much like those of 

 Dictvota. 



