150 ZOOPHYTES. 



The general colour of the exterior of the body is a yellowish-green. 

 The tubercles have a dark sap-green colour; they become obsolete 

 below, yet the green line continues to the base of the animal. The 

 colours of the tentacles are various and shaded like those of the prism ; 

 the disk is dull greenish, becoming darker towards the base of the ten- 

 tacles, and the mouth is flesh-coloured. J. DRAYTON. 



This species occurs, buried in the sand, and also attached to pebbles 

 or shells, two or three inches below the surface. When left by the 

 tide, it is easy to mistake the hole in the sand which covers them, for 

 the water-tubes of a Mya. On contracting, water spurts from various 

 small lateral orifices, as from a watering-pot. C. PICKERING. 



GENUS II. METRIDIUM. OKEN. 



Actinidce basi affixes, aliis tentaculis simplicissimis, nudis, et aliis tenta- 

 culis vel appendidbus frondescentibus, aut marginalibus, aut spar sis. 



Actinida? attached at base, having some simple naked tentacles and 

 other frondescent tentacles or appendages, either marginal or scat- 

 tered over the disk. 



METRIDIUM PRETEXT. (Couthouy.) 



M. cylindricum, maximum, 2J" crassum et scspe 6" elongatum, extus leve, 

 basi vix dilatatum et margine bene crenatum, crenaturis 2'" latis ; ten- 

 taculis internis, 2-seriatis, longis (1^") et flagelliformibus, subvalidis ; 

 externis paulo brevioribus, 3'" latis, frondescenter ladniatis aut subti- 

 liter bbatis, latere coalitis et apice tantum liberis, superfaie ports 

 tubulatis paudbus instructd. 



Very large cylindrical, 2 inches in diameter, and often 6 inches 

 long, exterior smooth, base scarcely dilated and neatly crenate at 

 margin, with the crenatures a sixth of an inch broad ; inner tenta- 

 cles long (1J inches) and flagelliform, rather stout; external a little 

 shorter, 3 lines wide, frondescently laciniate or delicately lobed, 



