622 



THE WONDERS OF GEOLOGY. 



Lt-ct. VI. 



with sea-water, and thus causing them to protrude. The 

 cells also contain water, with which the whole or any part 

 of the body can be filled ; and I have observed that when 

 the animal is desirous of shifting its situation, it distends 

 one half of the body with water, then withdraws the base 

 from the stone, and sinks to the bottom of the vessel in 

 which it is contained. This plan of the internal structure 

 of the Actinia (Lign, 137), will serve to illustrate these 

 remarks. The surface of the stomach, and even the inter- 

 nal lining of the tentacula, are abundantly furnished with 

 cilia ; these zoophytes have no durable skeletons. 



22. Caryophyllia, and 

 turbinolia.— In this small 

 recent coral {Turbinolia ru- 

 ber) we have an example of 

 a single calcareous cell, di- 

 vided by vertical lamellae or 

 partitions, arranged in a ra- 

 diated manner. This cell is 

 the skeleton or stony support 

 of a single polype, having a 

 double row of tubular ten- 

 tacula, and bearing a great 

 analogy to the Actinia ; in- 

 which communicate with each other deed, the recent animal may 



and with the tentacula. c, c, The ten- , dp<w»rihpd as an Actinia 



tacula. The surface of the stomach is D ^ ueSCllDeCl as an ACHllia 

 seen in the centre, arranged in vertical with a calcareous skeleton, 



plaits or folds. fi xe( i Dy j ts base# The fossil 



Turbinolia (ante, p. 320, fig*. 1, 2), and Caryophyllia 

 (fig. 3.), possess a similar structure. A beautiful living 

 Turbinolia, which is marked with red and white bands, 

 is shown in PL VI. fig, 8 : and a similar coral with its 

 tentacula expanded, in fig. 14. 



* By Dr. Robert B. Todd ; Cyclopaedia of Anatomy and Physiology, 

 p. 614. 



Lign. 137. — Illustration of the 

 structure of the actinia.* 



«, o, The base by which the actinia 

 attaches itself, b, b, Openings of cells 



