CORALS AND CORAL MAKERS. 5 



I. ACTINOID POLYPS. 



'J'he highest of Actinoid Polyps are those of the Actinia 

 iKiBE — the species that secrete no coral to clog vital action 

 and prevent all locomotion. The details of structure may be 

 best described from the Actinia or Sea-anemone, and aftei- 

 ward the distinguishing characters of the coral-making polyps 

 may be mentioned. In external aspect and in internal charac- 

 ters all are essentially identical. 



I. NON-CORAL-MAKING POLYPS. 



As the figures on the frontispiece, and also the following, 

 show, the external parts of an Actinia are — a subcylindrical 

 body— a disk at top — one or more circular series of tentacles 

 making a border to the disk — a mouth, a merely fleshy, tooth- 

 less opening, at the centre of the disk, sometimes at the 

 summit of a conical prominence — a basal disk for attachment. 

 The upper extremity is called the actinal end, since it bears 

 the tentacles or rays, and the lower or base, the abadhial. 



Sea-anemones vary greatly in colour, and in the distribution 

 of their tmts. The lower figure on the frontispiece represents 

 one variety of the Fhy?tiaclis clematis from Valparaiso. Another 

 variety of the same lias a rich deep green colour. The upper 

 species on the same plate is one of the gorgeous varieties of 

 the Phymadis florida from Callao, Peru. Another is green 

 throughout ; and another has a pale bluish-green disk with 

 purplish tentacles, and the papillae of the body dark sap-green 

 on a pale reddish ground. The other species is the Biuiodcs 

 ganma, from Porto Pray a. Cape Verd. It is one of the warty 

 species, and is but partly expanded. The same is shown un- 

 expanded m figure 3^;, on the right, with disk and tentacles, as 

 usual in this state, wholly concealed. 



While often brilliantly coloured, especially in the tropics, 

 other Actiniai are nearly colourless. This was the case with 

 that represented in the following cut, a species from Long 

 Island Sound near the New Haven Lighthouse, figured some 

 twenty years since by the author, but left undescribed. The 



