XOW- WATER MAEK. 77 



Tlie rock-pools now so deep and clear have most of 

 the seaweeds from the upper pools in larger growth ; 

 the Corallines is dense, and beautifully tinted witli its 

 own delicate blush, of red, and the parasitic rosy 

 Callithamnion. There are long coils of the Chorda 

 Filum, probably with bunches of Ceramium, thick 

 forests of Cystoseira and Halidrys, laden with delicate 

 fronds of rarer seaweed. Look calmly down, and pick 

 the small feathery tufts for examination at home. 



As we now find a variety of Folysiphonias, it will 

 be as well to give the generic character of the tribe. 



POLTSIPHOMA. 



(Xame from the Greek, signifying "many siphons," or tubes, alluding 

 to the number in the stem.) 



Generic character. — Frond thread-like, partially or 

 generally jointed, joints longitudinally striped, com- 

 posed internally of parallel tubes ranged round a cen- 

 tral cavity. 



Fructification. — Double or distinct plants. 1. Ce- 

 ramidia, or urn-shaped cells containing pear-shaped 

 spores. 2. Tetraspores, or group of four spores, im- 

 bedded in swollen branchlets. 



Poltsiphoxia BTSSoiDis. — At low-water mark 

 and in four or five fathom water, seek this beautiful 

 species : it will be seen floating out from stones or 

 shells, probably under masses of shadowy Laminaria: 

 It is one of the handsomest of all the JPolysiplionias • 

 both in the book, where it becomes a dark red-brown, 

 or fresh in the water a crimson lake, spreading from a 



