CONFERVACEiE. 277 



green sporidia are developed ; nodes constricted. — Hoemo- 

 trichtjm, from the Greek hormos, a necklace, and trichoma, 

 hair. 



All the species of this genus are marine, and were 

 formerly included in the genera Conferva and Lyngbya. 

 They differ from the Chcetomorphce in habit and texture, 

 and in the changes that take place in the endochrome. 

 They all grow on rocks, etc., between the tide-marks. 



Hormotrichum Younganum. Young's Hormo tri- 

 es hum. 



Threads from one to three inches long, about as thick as 

 human hair, erect, straight or curved, of a bright green 

 colour, not glossy, and but slightly gelatinous, growing in 

 tufts on rocks, etc. ; cells varying in length from rather 

 shorter than they are broad to nearly twice as long ; those 

 of young threads which are increasing in length are quite 

 filled with endochrome, and divide transversely in the centre, 

 each half becoming a perfect new cell ; those of mature 

 threads have the endochrome in a dense mass, which even- 

 tually becomes a sporidium in their centre. 



This is a summer annual, and grows near high-water 

 mark in many localities on the British coast. It does 

 not adhere very closely to paper when dried. 



Hormotrichum collabens. The collapsing Hor- 

 motrichum. 



Threads from three to six inches long, robust, those of the 

 same tuft varying much in diameter, of soft, gelatinous 

 texture, and bright verdigris-green colour ; cells from once 

 to once and a half the length of their diameter, filled with 

 a dense mass of bright green granular endochrome, and 

 having thick walls. 



