CONFERVACE^. 89 



V. HORMOTRICHUM, Kutz. 



Filaments gelatino-membranaceous, unbranched (or with a few rootlike branches), 

 basifixed, articulated ; formed of a string of very short cells. Cell-wall very thick and 

 soft. Nodes constricted. Articulations often tumid, filled with dense, green, granular 

 endochrome, which is finally converted into darker-coloured compact sporidia. (Marine.) 



The plants comprised under this genus have hitherto been placed either in Conferva 

 or in Lynghya. They all have a peculiar habit, by which they are more readily known 

 than by any definite character at present established. The changes that take place in 

 the endochrome will probably afibrd better characters when they have been carefully 

 ascertained and compared with what occur in Chcetomorpha. At present we are con- 

 tented to refer to this place all the soft, sub-gelatinous, marine Confervae, which are 

 basifixed, and have short joints — the type of these being C. Youngana, Dillw. ; and 

 such Lyngbya-\ike Algae as Lyngh. Carmichaelii and its allies, whose truly articulated 

 tube distinguishes them from proper Lynghya. The whole assemblage of species which 

 are thus brought together are remarkable for the brilliant green of their endochrome, 

 which at first fills the cells, and is afterwards contracted and condensed, and for the 

 breadth of the soft, sub-gelatinous, glassy cell-wall. At maturity the wall of the cell 

 opens, and the compact sporidium escapes. All the species are natives of littoral rocks 

 and objects growing within tide marks. Three of the following are European. 



1. HoRMOTRiCHUM Younganum, Dillw. ; filaments short or elongated, tufted, capil- 

 lary, rather firm, grass-green, not remarkably gelatinous, nor glossy when dry ; articu- 

 lations as long, or once and half as long as broad, or shorter than their breadth, tumid, 

 constricted at the nodes. Dillw. Conf. t. 102. Harv. Phyc. Brit. t. 328. Kiitz. Sp. 

 Alg.p. 382. 



Hab. On stones and wood-work, between tide marks. New York Bay, Mr. Congdon. 

 Common at Fort Hamilton in spring. W. H. H. (v. v.) 



Filaments densely tufted, 1-3 inches long, as thick as human hair, erect, straight or 

 curved, spreading over the surface of rocks and wood-work in grass-green fleecy tufts, 

 not lubricous or gelatinous (as compared with others of the genus), soft, but rather 

 firm. The filaments when young are cylindrical, but soon become constricted at the 

 dissepiments or nodes. The cells vary much in length, even in the same filament. The 

 common length is once and half as long as broad, but they are sometimes twice as long, 

 sometimes only as long as their diameter, and sometimes only half as long. At first 

 they are quite filled with the granular deep-green endochrome, which, while the filament 

 is elongating, divides in the centre, forming two new cells from each old one ; but in the 

 mature plant it gradually condenses, and retreats toward the centre of the cell, where it 

 forms a compact, globose or oval sporidium. In drying the filaments adhere, but not 

 strongly, to paper. 



