562 



NATURAL HISTORY 



THE MERMAN'S SHAVING BRUSH, 

 Penicillus capitatus, from Bermuda. (About 

 one half natural size) 



a storm on Long Island, Martha's Vine- 

 yard, and Nantucket. As is well known, 

 it is accompanied by a characteristic fauna 

 of bryozoa, crustaceans, small mollusks, 

 and the like, and fishes which go along 

 with it to feed on the small animals that 

 it carries. Species of Sargassum are diffi- 

 cult to limit and define, but it is safe to 

 say that a dozen or more occur in the West 

 Indian region. Most of these are surf 

 plants, growing firmly attached to rocks 

 and reefs in exposed places. They are 

 found near the low-water mark, and, with 

 their cousins of the genus Turbinaria, they 

 take the place, in the south, of the north- 

 ern rockweeds of the genera Fucus and 

 Ascophyllum, both taxonomically and eco- 

 logically, although never so conspicuous 

 ami massive as the latter often are. 



The genus Sargassum, like all the other 

 alg», belongs to the large group of plants 

 known in the books as "thallophytes" — a 

 group in which the plant body, according 

 to the bookmakers, is not differentiated 

 into root, stem, and leaf; yet it is very 

 difficult, if not impossible, to frame a defi- 

 nition of a leaf which may not apply to 

 the leaflike structures shown by the species 

 of Sargassum. In other words, a Sargassum 



is a "leafless" plant that appears to have 

 leaves. 



The larger algae are divided into three 

 great groups, which are often spoken of in 

 an untechnical way as the "greens," the 

 "browns," and the "reds," these names 

 being abbreviated translations of the tech- 

 nical group names, which have been based 

 upon the prevalent colors shown by repre- 

 sentatives of these groups. The "browns" 

 include the largest kinds of seaweeds, such 

 as the kelps and rockweeds of the North 

 Atlantic and the giant kelps of our Pacific 

 coast, individuals of which often reach a 

 length of more than one hundred feet and 

 the extensive beds of which are now being 

 used as a source of potash for the Ameri- 

 can farmer and gardener. In the American 

 tropics, the more conspicuous members of 

 the brown group include, besides Sargas- 

 sum and Turbinaria, already mentioned, 

 representatives of several other genera. 



It is perhaps in the large group of algae 

 known colloquially as the "greens" that 

 one finds the most interesting and curious 

 as well as the most beautiful of the tropi- 

 cal sea plants. In these, the leaf-green or 

 chlorophyll, characteristic of plants in 

 general, is found essentially free from ad- 

 mixture with other pigments. In many of 

 them, however, the plant body is more or 

 less coated or permeated with lime, so that 

 it is often whitish, at least in the older 

 parts, or speedily becomes so after being 

 taken from the water and exposed to the 

 light. 



Of the group of calcified green algae the 

 four species of Penicillus, indigenous to the 

 sea bottoms of Bermuda, southern Florida, 

 and the West Indies, are among the most 

 curious. In these, as is suggested by the 

 Latin name, the plant body takes the form 

 of a brush, its component filaments being 

 closely interwoven to make a cylindric or 

 flattened stalk and then, at the top, set 

 free and forking, each enclosed in a porous 

 sheath of lime, they constitute the head or 

 bristles of the brush. One sort, perhaps the 

 commonest, is sometimes known as the 

 merman's shaving brush, or is occasionally 

 referred to by the less particular and 

 meticulous as the mermaid's shaving brush. 

 A relative of the plant just described and 

 one that grows in similar situations is the 

 mermaid's fan. There are several species 

 of this generic group (Udotea), in all of 



