186 ANTHOZOA IIELIANTHOIDA. 



pears as a pulpy substance. Intimately intermixed with it, 

 in irregular patches, and not constituting a distinct or separate 

 layer, is a pigment varying in colour in different parts of the 

 same animal, and in different individuals. This colouring 

 matter is extensively distributed over the base, sides, tentacula, 

 and roof, but I have never observed any trace of it in the 

 stomach."* The surface is either smooth or studded over 

 with jiorous wai-ts, which, having an adhesive quality, enable 

 the creatures the more completely to conceal themselves by 

 induing the body with an extraneous coat formed of the sand, 

 gravel, and broken shells which lie around their peculiar locali- 

 ties. This is exchanged in the madrecolous tribes for the 

 more perfect defence which a hard coral affords, into which 

 the soft parts are withdrawn at will. " This coral is calcare- 

 ous, and the cells which are inhabited by the animals are fur- 

 nished with more or less distinct longitudinal lamelke, placed 

 in a radiating position round the central axis, so as to give the 

 cavity a star-like appearance.""!" Its structure is in fact a 

 model cast in lime of what may be called the skeleton of the 

 Actinia?, — the parts on which the support depends being con- 

 verted into stone by a deposition of calcareous matter in their 

 texture, — the corium in this manner becoming a solid polypi- 

 dom, and the muscular leaflets partitions of limestone.| 



When a Helianthoid Polype is at rest and unalarmed, it 

 can dilate the body to fully twice its ordinary bulk by imbib- 

 ing water through the mouth or tentacula, § the bases of which 



* Teale in loc. 95. f Gray in Synop. of British Museum, 70. 



{ " Dans cette classe cPanimaux, le polypier ou la partie solide qui reste quand le 

 partie animale a ^te dessechee et enlevee, est done une sorte de reseau calcaii'e d\in 

 tissu plus ou moins compacte, qui remplissoit Ics mailles, les vacuoles de celle-ci. La 

 proportion de ces deux parties est en rapport avec Page da zoanthaire : plus il est 

 jeune, plus il y a de matiere animale ; plus il est Age, et plus il y a de raatiere 

 inorganique: aussi la base de ces polypiers, le plus souvent morte, est-elle fort 

 dure, tandis que le sommet ou les bords essentiellement vivans sout entierement 

 mous." Blainville, Actinolog. 311. — See also Harvey in Mag. Nat. Hist. n. s. i. 

 474. 



§ " It has not, so far as I know, been clearly shewn by which of the communi- 

 cating orifices the water enters. Though I took considerable pains, I have not been 

 able satisfactorily to ascertain this point. I may remark, however, that I have re- 

 peatedly noticed water entering at the mouth." Sharpey in Cyclop. Anat. and 

 Phys. i. G14. — Delle Chiaje asserts that it enters by the tentacula. Bull, des Sc. 

 Nat. xvii. 471. He adds, " II est curieux d'observer le courant d'eau qui, lorsque 



