252 Dr. Johnston's Catalogue of Zooyhtes. 



Hab. Parasitical on various sea weeds, from deep water, very common on this coast. 



Polypidom variously branched, often proliferous, sometimes sub -cylindrical, commonly 

 flattened and palmate, of a dirty straw-yellow colour, often partially stained with red, and 

 marked with numerous yellowish circular spots, irregularly disposed. It is thickish, some- 

 what cartilaginous, and to the naked eye resembles a compact sponge. When viewed 

 through a common magnifier, the surface is seen to be covered with close-set conical 

 transparent papilla, each of which is a cell containing a polype, with sixteen equal long 

 filiform tentacula, arranged in a circle. 



The yellowish spots, mentioned in the above description, are produced by clusters of 

 ova, lying embedded in the cellular texture of the polypidom. Each cluster is composed of 

 about ten ova, which are globular, milk white, and opake. Removed from the polypidom 

 and placed in a watch glass filled with sea-water, I found them moving with great rapidity, 

 and in all directions. The progressive motion is very obviously effected by the ceaseless 

 pby of a fine thick fringe of ciliae, which surrounds two-thirds of their circumference. They 

 have also a rotatory motion, and a globule may often be observed moving forward and 

 whirling on its own axis at the same time. 



2. A. echinatum, polypidom incrusting dead univalve shells ; papillae or polype-cells rough- 

 ened ; the polypes with twelve tentacula (tab. nost. ix. f. 2). 



A. echinatum, Flem. Br. Anim. 517. 



Hab. Parasitical on Buccinum undatum and other univalves, not common on this coast. 



"This species incrusts dead univalve shells exclusively; and is about the 2 \j of an inch 

 in thickness. When first taken out of the water it is soft and spongy, but becomes rigid 

 on drying." — Fleming. The surface, in this state, is muricated with rigid obtuse papillae, 

 somewhat less than a line high, and themselves roughened with minute prickles pointing 

 upwards and arranged in rows. It seems to have been first observed by Mr. Montagu. 



IV. Z. THECATA. 



6. TUBULARIA. 



1. T. indivisa, tubes clustered, simple, cylindrical, narrowed and interwoven at the base : 

 head of the polype crested with two rows of tentacula. — Oaten-pipe Coralline. 

 T. indivisa, Linn.; Soland. Zooph. 31; Turt. Lin. iv. 666; Turt. Brit. Faun. 210: 

 Stew. Elem. ii. 437 ; Lam. Hist. Nat. ii. 110 ; Bosc. Vers. iii. 89, t. 28, f. 5, a reduced 

 copy of Ellis's ; Lamour. Corall. 100 ; Flem. Br. Anim. 552. 

 T. Coralline, like oaten pipes, Ellis Corall. 31, t. 16, f. C. ; Phil. Trans, xlviii. tab. 17, fig. D. 

 Adianti aurei minimi facie planta marina, Rail. Syn. 31, No. 4. 

 Hab. On shells and stones from deep water, not uncommon. 



The tubes are simple, or sometimes divided at the base, where they are twisted and 

 Sexuose, fistular, even, continuous, horn-coloured, 6 inches or upwards in height, and 



