THE SEA MAT. 365 



in its soft, plumy branches to such an extent that it marches beneath their shade, like 

 Macduff's army under its leafy disguise. I know scarcely a more wonderful sight than is 

 presented by a living sj^ecimen of the Bugula, with its wonderful appendages in full action. 

 As if moved by machinery, they nod up and down like automata, sometimes throwing them- 

 selves back like the head of a fan-tail pigeon ; the mouth opens slowly, with a wearied kind 

 of air, that almost forces the observer to yawn in sympathy with the deliberate movement, 

 while ever and anon the jaw suddenly closes with a snap so sharp that the ear instinctively 

 watches for the sound. 



Eveey one who has walked along the sea-shore must have observed the pretty, leaf-like 

 Sea Mats strewn on the beach, and admired the wonderful regularity of their structure, per- 

 ceptible to the naked eye ; but when magnified even by a pocket lens, their beauty increases 

 in proportion to the power employed, and the marvellous arrangement of the cells, and the 

 orderly system in which they are placed, are almost beyond belief. Beautiful, however, as 

 they are in this state, they are but the dead and lifeless habitations of the creatures who built 

 the wondrous cells, and the only method of showing the Sea Mat in its full glory, is to take a 

 living specimen from the stone or shell to which it is affixed, and watch it under the micro- 

 scope wdrile the creatures are still in full activity. The common Sea Mat is sometimes called 

 the Hornwrack. 



The peculiar manner in which the polypes of the Sea Mat protrude themselves is quaintly 

 and accurately described by Mr. Gosse in his " Evenings at the Microscope." After pointing 

 out the cradle-like shape of the cells, he proceeds as follows: " Suppose that a coverlid of 

 transparent skin were stretched over each cradle from a little within the margin all round, 

 leaving a transverse opening just in the right place, viz., over the pillow, and you would have 

 exactly what exists here. There is a crescent-form slit in the membrane of the upper part of 

 the cell, from which the semicircular edge and lip can recede if pushed from within. 



" Suppose, yet again, that in every cradle there lies a baby with its little knees bent up 

 to its chin, in that zigzag posture that children, little and big, often like to be in. But stay, 

 here is a child moving ! Softly and slowly pushes open the semicircular slit in the coverlid, and 

 we see him gradually protruding his head and shoulders in an erect position, strengthening 

 his knees at the same time. He is raised half out of bed, when lo ! his head falls open, and 

 becomes a bell of tentacles. The baby is the tenant polype." 



The Toothed Sea Mat is a variation with curious tooth-like appendages from which it 

 derives its name. 



A curious polyzoon, bearing the name of Carbasea episcopalis, is found in Bass's Straits at 

 a depth of forty-five fathoms. This species is found in two forms, either parasitic on sertularia 

 and various polyzoa, and then of small size, or leading an independent existence, and reaching 

 considerable dimensions. It is chiefly remarkable for the singular form of the ovicells, which 

 bear a wonderfully close resemblance to bishops* mitres, and have earned for the species the 

 title of episcopalis. 



Two specimens of another genus are called Diachoris magellanicus and Diachoris 

 crotali. The latter shows remarkable appendages which guard the mouth ; and the former, 

 Dfachoris ■magellanicus, exhibits the method in which each cell, except at the margins of the 

 fronds, is connected with six others, something like the stellate cells in pith. In fact, the 

 Diachoris is a flustrum dissected, the cells being drawn away from each other and connected 

 by stalks. The central cell is by connecting stalks united to the six that surround it. 



Any one who picks up a piece of a dark sea-weed, will find that many parts of its structure 

 are covered with a peculiar growth, that looks as if a portion of Sea, Mat had been cemented 

 upon it. This substance is indeed closely allied to the Sea Mat, and is chiefly to be distin- 

 guished by the membranous nature of the polyzoary, which will not permit it to stand boldy 

 erect after the manner of the true Sea Mat. This species is called Membranipora pilosa. 



The leathery plume of tentacles is extremely graceful, and, when the creature is living, 

 has a remarkably elegant effect. In a specimen now before me, viewed by a power of only 

 thirty diameters attached to the binocular microscope, the polypes of the Membranipora are 



