Fig. 11 is the Sphacelária, so called from the curious capsule cells found at the end of the branches, and termed sphacelæ. This portion of the plant is shown more magnified in Fig. 12. Another sea-weed is represented in Fig. 13, in order to show the manner in which the fruit is arranged; and a portion of the same plant is given on a larger scale at Fig. 14. A very pretty little sea-weed called Cerámium is shown at Fig. 15; and a portion showing the fruit much more magnified is drawn at Fig. 22. Fig. 23 is a little alga called Myrionéma, growing parasitically on the preceding plant. Fig. 16 is a section of a capsule belonging to the Hálydris siliquósa, showing the manner in which the fruit is arranged; and Fig. 17 shows one of the spores more magnified. Fig. 18 shows the Polysiphónia parasítica, a rather common species of a very extensive genus of sea-weeds, containing nearly three hundred species. Fig. 19 is a portion of the stem of the same plant, cut across in order to show the curious mode in which it is built up of a number of longitudinal cells, surrounding a central cell of large dimensions, so that a section of this plant has the aspect of a rosette when placed under the microscope. A capsule or “ceramídium” of the same plant is shown at Fig. 20, for the purpose of exhibiting the pear-shaped spores, and the mode of their escape from the parent-cell previous to their own development into fresh plants. The same plant has another form of reproduction, shown in Fig. 21, where the “tetraspores” are seen imbedded in the substance of the branches. There is yet a third mode of reproduction by means of “antheridia,” or elongated white tufts at the extremities of the branches. The cells produced by these tufts fertilise the rudimentary capsules, and so fulfil the function of the pollen in flowering plants. Fig. 25 is the Cladóphora, a green alga, figured to illustrate its mode of growth; and Fig. 26 represents one of the red sea-weeds, Ptilóta élegans, beautifully feathered, and with a small portion shown also on a larger scale, in order to show its structure more fully. A good contrast to this species is seen on Fig. 27, and the mode in which the long, slender, filamentary fronds are built up of many-sided cells is seen just to the left hand of the upper frond. Fig. 24 is a portion of the lovely Delesséria sanguínea, given in order to show the formation of the cells, as also the arrangement by which the indistinct nervures are formed. V.