ALG^ CONTliVUED: CLASSIFICATION. 



171 



Classification. — KjcUman dividus the Phx-oph\'(.ea:- into two orders. 



369. Order Phseosporalea (Phseosporeae) including 18 families. One of 

 the most conspicuous families is the Laminariacea-, including among others 

 the (iiant Kelps mentioned above (Laminaria, Postelsia, Macrocystis, etc.). 



370. Order Cyclosporalea (Cyclosporeae). — This includes one family, the 

 Fucacea: with Ectocarpus, Sphacelaria, La-athesia, Fucus, Sargassum, etc. 



Class Rhodophyceee. 



371. The red algse (Ehodophyceaej. — The larger number of the so-called 

 red algse occur in salt water, though a few genera occur in fresh water. 

 The plants pjossess chlorophyll, but it is usually obscured by a reddish or 

 purpjle pigment. 



372. Nemal'on. — This is one of the lower marine forms, though its thal- 

 lus is not one of the simplest in struc- 

 ture. The plant body consists of a 

 slender cylindrical branched shoot, some- 

 times very profusely branched. The 

 central strand is rather firm, while the 

 corte.x is composed of rather loose fila- 

 ments. 



373. Batrachospermum. — This genus 

 occurs in fresh, water, and the species 

 are found in slow-running water of 

 shallow streams or ditches. There is a 

 central slender strand which is more or 

 less Vjranched, and on these branches 

 are whorls of densely crowded slender 

 branches occurring at regular intervals. 

 The plants are usually ven.- slipper)'. 

 Gonidia are formed on the ends of some 

 of these branches in globose, sporangia, 

 called monosporangia, since but a single 



... . . , , . , A red alga (Nemalion). .4 



spore or gomdium is developed in each, branehes. showing antheridia 



Other branches often terminate in long ^arpogomum o . 



^ tncnogi'ne ((), to wnicn are attached. 



sexual 



(a): 



carpogonium or procarp io) with its 



slender hyaline seta^ 

 fresh water. 



two spermatia {s)\ B, beginning of 

 „„. _ _,, . , a cystocarp (o), the trichogvne (t) 



374. Lemanea. — This genus also occurs still showing; C, an almost mature 



trichugyne (i). {After Vines.) 



The species develop J>:"V^=^''P (?''"'^* f*"= 4!?°rganizing 

 onl}' during the cold winter months 

 rapids of streams or \\-here the water from falls strikes the rocks and is 

 thoroughly aerated. They form tufts of greenish threads, cylindrical or 

 whiplike, which in the summer are usually much broken down. The 

 threads are hollow and have a firm corte.x. These are the sexual shoots, 



