92 BRITISH SEA-WEED3. 



ing tetraspores, they should be as carefully preserved a 

 their more luxuriant brethren. 



Genus XXXIX. BOSTRYCHIA. 



Frond of a dull purple colour, thread-like, inarticulate, 

 composed of a tubular, jointed axis, surrounded by oblong 

 coloured cells, which become shorter towards the circum- 

 ference, those at the surface being square, and giving the 

 plant the appearance of being dotted. Spores pear-shaped, 

 arranged in tufts in ovate, terminal conceptacles ; tetra- 

 spores tripartite, in double rows, in spindle-shaped, terminal 

 stichidia. — Bostetchia, from the Greek hostrt/chos, a curl. 



This is a rather extensive genus of small sea-weeds, 

 all of a dull purple colour, and growing usually near 

 high-water mark, or in places which are only occasion- 

 ally submerged. They have no objection to brackish 

 or even perfectly fresh water, and are sometimes found 

 in streams at a considerable distance from the sea. 

 These peculiarities are the more remarkable, as most 

 of the species of the allied genera grow in depths wliere 

 they are rarely exposed by the receding tide, and where 

 they are far removed from all chance of contact with 

 fresh water. The species are widely distributed in 

 warm and temperate latitudes, several being abundant 

 at the njouths of the rivers running into the Gulf of 

 Florida, and on the adjacent coasts of North and South 

 America; one occurring in Kerguelen's Land, and 

 others on the Atlantic shores of Europe. 



Bostrychia scorpioides. Scorpion-like Bos- 

 trychia. 



Fronds two to four inches high, growing in matted tufts, 



