[Illustration: FIG. 72.--_Sargassum bacciferum_. A portion of the thallus, natural size.] Order 1. =Fucaceæ.= The following species are common on our coasts: _Fucus vesiculosus_ (Fig. 70) has a thallus with an entire margin, and with bladders arranged in pairs; _F. serratus_ (Fig. 71) without bladders, but with serrated margin; _Ascophyllum nodosum_ has strap-like shoots, which here and there are swollen to form bladders; _Halidrys siliquosa_ has its swimming bladders divided by transverse walls; _Himanthalia lorea_, which is found on the west coast of Norway, and the south coast of England, has a small perennial, button-shaped part, from the centre of which proceeds the long and sparsely branched, strap-like, annual shoot, which bears the conceptacles. The Gulf-weed (_Sargassum bacciferum_, Fig. 72) is well known historically from the voyage of Columbus; it is met with in large, floating, detached masses in all oceans, and is found most abundantly in the Atlantic, off the Canary Islands and the Azores, and towards the Bermudas. The stalked, spherical air-bladders are the characteristic feature of this genus. The thallus is more highly developed than in _Fucus_, and there is a contrast between the stem and leaf-like parts. The portions which are found floating are always barren, only those attached are fertile. USES. The Fucaceæ, like the Laminariaceæ, are used as manure (the best kinds being _Fucus vesiculosus_ and _Ascophyllum nodosum_), for burning to produce kelp, and as food for domestic animals (_Ascophyllum nodosum_ is especially used for this purpose). Class 9. =Dictyotales.=