SERTULARIADiE : SERTULARIA. 



65 



Fig. 9. 



pale horn colour, pellucid, variously branched, the branches bifarious, 

 alternate, patent, similar to the stem. Cells opposite, with a joint 

 between each pair, rather long, tu- 

 bular, creased, the upper half sud- 

 denly divergent, with an oblique entire 

 wide aperture. (Fig. 9.) The inter- 

 nodes are often much constricted at the 

 joint, which is sometimes apparently 

 twisted. Ellis compares the vesicles 

 to a " Lily or Pomegranate flower just 

 opening," but Pallas asserts that the 

 comparisons, as well as the figures of 

 them in Ellis's work, are inaccurate, 

 — a criticism the truth of which Ellis 

 denies in his subsequent volume on 

 zoophytes. They appear in fact to 

 vary somewhat according to their 

 age, and also from the manner in 

 which they have been dried, for, from 

 the thinness of their texture, they 

 are more liable than in other species 

 to become creased and folded irresfu- 

 larly. In general they are subsessile and very exactly pearshaped, 

 with a lanceolate segment on each side, the segments converging and 

 partially covering the puckered centre, like the leaves of a cabbage 

 round its heart (fig. 9.) ; but there is considerable variety in their 

 figure and structure. Pallas says that they are hexangular, and 

 have six subulate and patent spines above, so as to resemble the 

 capsules of the Nigellas. In some good specimens sent to me by 

 Mr. Peach from Cornwall, the capsules are not only considerably 

 smaller than usual, but the acute apex is entire in some cells, and in 

 others furnished with one or two minute spines. These capsules 

 are probably immature, and have not yet opened to discharge their 

 contents. 



Sert. rosacea, according to Mr. W. Thompson, " is much more 

 delicate and graceful when springing from the stems of its kindred 

 zoophytes (Sertularia argentea, Plumularia falcata, &c.) than from 

 those of the tangle (Laminaria digitata) : the colour, too, is lighter 

 and of a more agreeable hue in the former instance. In the same 

 locality (Belfast bay) it differs thus, accordingly as it emanates from 

 zoophytes or the Laminaria. The more robust development of S. 



F 



