20 HANDBOOK: OF SEA-WEEDS. 



The species of Elachista, composed of minute parasites, are, 

 as well as unattractive like the Mesogloiese, inconspicuous, but 

 are beautiful objects when placed under the microscope. My- 

 rionemse are also parasitic, and even smaller than the plants of 

 the preceding genus. 



In the Dictyotese the frond is mostly flat, with a reticulated 

 surface, which is sprinkled when in fruit with groups of naked 

 spores or spore cysts. This tribe includes not a few of the most 

 elegant among the Algae. In structure they are coriaceous, and 

 include plants both with broad and narrow, branched and un- 

 branched fronds. In Haliseris there is a distinct midrib. The 

 largest of the British Dictyoteae is Cutleria multifida, sometimes 

 found a foot and a half long ; and the best known is doubtless 

 Padina pavonia, much sought after by seaside visitors where it 

 grows. Its segments are fan-shaped, variegated with lighter 

 curved lines, and fringed with golden tinted filaments. (Fig. 1 1.) 

 Owing to its power of decomposing light, its fronds, when growing 

 under water, suggest the train of the peacock, whence its specific 

 name. Taonia atomaria somewhat resembles Cutleria, but exhibits 

 also the wavy lines of Padina. The plant of this group most 

 often cast ashore is Dictyota dichotoma. It makes a handsome 

 specimen when well dried, and is interesting on account of the 

 manner in which it varies in the breadth of its divisions. The 

 variety intricata is curiously curled and entangled. Dictyosiphon 

 fceniculaceus, the solitary British example of its genus, is a bushy 

 filiform plant, remarkable for the beautiful net-like markings of 

 its surface. The Punctariae have flattened fronds, marked with 

 dots, which sufficiently distinguish them from all the others. A 

 small form is often found parasitic on Chorda filum, spreading 

 out horizontally like the hairs of a bottle brush. Asperococcus 

 derives its name from its roughened surface, occasioned by 

 the thickly scattered spots of fructification. 



The Laminariacese are inarticulate, mostly flat, often strap- 

 shaped. Their spores occur in superficial patches, or covering 

 the whole frond. The plants of this order, as we have already 

 seen, include the giants of submarine vegetation. In point of 

 mass they constitute the larger part of our native Algae, although 

 they number only a few species. They are popularly known as 

 tangle or oarweeds, and the stems of Laminaria saccharina and 

 the midrib of Alaria esculenta are used as food. 



The Sporochnaceae are a small but beautiful tribe, inarticulate, 

 and producing their spores in jointed filaments or knob-like 

 masses, and remarkable for their property of turning from olive 

 brown to a verdigris green when exposed to the atmosphere. 



