XIV ZOANTHARIA ACTINIARIA 379 



gemmacea, etc., the embryos are discharged into the water from 

 the body-cavity of the parent, at a stage with six or twelve 

 tentacles. In the Arctic species of the genera Urticina and 

 Actinostola, however, the embryos are retained within the body 

 of the parent until several cycles of tentacles are developed, and 

 in Urticina crassicornis the young have been found with the full 

 number of tentacles already formed. In Epiaetis prolifera from 

 Puget Sound, the young Anemones attach themselves to the body- 

 wall of the parent after their discharge, and in Upiactis marsu- 

 pialis, Fseudophellia arctica, Epigonactis fecunda, and other species 

 from cold waters, the young are found in numerous brood sacs 

 opening in rows on the body- wall. It is not known for certain 

 how these embryos enter the brood sacs, but it is possible that 

 each sac is formed independently for a young embryo that has 

 settled down from the outside upon the body-wall of the parent. 

 The most specialised example of this kind of parental care in the 

 Sea-anemones is seen in Marsupifer valdiviae from Kerguelen, in 

 which there are only six brood sacs, but each one contains a great 

 many (50-100) embryos. 



The wonderful colours of our British Sea-anemones are familiar 

 to most persons who have visited the sea-side. The common 

 Actinia mesembryanthemum of rock pools, for example, is of a 

 purple red colour. The base is usually green with an azure line. 

 Around the margin of the disc there are some twenty-five tur- 

 quoise blue tubercles. On each side of the mouth there is a 

 small purple spot, and the numerous tentacles forming a circlet 

 round the mouth are of a pale roseate colour. Nothing could be 

 more beautiful than the snowy-white Actinoloha dianthus or the 

 variegated Urticina crassicornis. 



Similar wonderful variety and beauty of colour are seen in 

 the Sea-anemones of other parts of the world. Thus Saville 

 Kent ^ in describing a species of the gigantic Stoichactis of the 

 Australian Barrier Eeef says, " the spheroidal bead-like tentacles 

 occur in irregularly mixed patches of grey, white, lilac, and 

 emerald green, the disc being shaded with tints of grey, while 

 the oral orifice is bordered with bright yellow." 



The order Actiniaria contains a large number of families, 

 presenting a great variety of external form and of detail in 

 general anatomy. The definitions of the families and their 

 1 Saville Kent, "The Great Barrier Reef," 1893, p. 144. 



