ITS INHABITANTS AND GUESTS. 11 



prominent gizzard, may be distinctly seen. The polypide has ten 

 ciliated tentacles, and is often figured as an illustration of polyzoan 

 structure in works on natural history. 



Before parting with our specimen of Flustra, we notice (see 

 Plate I., Fig. i e) running along it a slender brown thread, ap- 

 parently knotted here and there, and sending off short erect shoots. 

 Occasionally a larger knot appears ; this is not a polyzoon but a hy- 

 droid, Sertularella nigosa, or the "Snail-trefoil Coralline." Under 

 the lens the apparent knots are seen to be the calycles or cells of 

 the polyps, which are wrinkled and shaped like little barrels. The 

 larger knots are the reproductive capsules which have three teeth 

 at the upper end. Ellis gave this hydroid its popular name from 

 the resemblance of its cells to the seed-vessels of the " Snail- 

 trefoil " plant. It is a very common object on Flustra, but not 

 less beautiful on that account (see Plate II., Fig. 9). 



I have only named here a few of the many zoophytes (polyzoa 

 and hydroids) which find a resting-place on the Broad-leaved 

 HornwTack, but, as this is usually deemed so common as not to be 

 thought anything of, I considered it not inopportune to point out 

 that not only is it in itself an object of great beauty, especially when 

 freshly taken from the water and having its characteristic scent of 

 verbena or bergamot, but that it is even of greater interest as the 

 habitat of other interesting forms of zoophytes, which run the risk 

 of being overlooked and neglected owing to the universal distribu- 

 tion of their host. The generic name of the Flustra is derived from 

 the Anglo-Saxon y?//j/r/^;;, to weave ; and the richest lawns or silks 

 are not woven with greater delicacy than is manifested in the fronds 

 of the various species. As Dr. Landsborough remarked in speak- 

 ing of the genus, " He alone who gathered together the waters of 

 the sea could teach these marine manufacturers to construct amidst 

 its waves such elegant tabernacles." 



EXPLANATION OF PLATES L and IL 



Plate I. 



Fig. 1. — Frond of Flustra foliacea, showing growing upon it fa) Scrupo- 

 cellaria reptans, (b) Bugula avicularia^ (c) Crisia eburnia^ (d) 

 Diastopora patina, (e) Sertularella rugosa. 



