176 ACTINIAD.F. 



GENERAL DESCRIPTION. 

 Form. 



Base. Adherent to rocks ; considerably exceeding the column, outline 

 often long-oval. 



Column. Delicately smooth, without much excretion of mucus, wholly 

 imperforate, and non-adhesive. Substance fleshy, approaching to pulpy. 

 Form hemispheric in button, a low column in flower, much expanded at 

 the summit. Margin strongly developed, with a smooth, sharp edge, 

 boundiug a wide but shallow fosse, within which are seated a single series 

 of numerous spherules. 



Disk. Slightly concave, smooth ; the radii faintly marked. 



Tentacles. About two hundred in full-grown individuals, arranged in six 

 rows thus :— 6, b', 12, 24, 48, 96 = 192 ; moderately slender, shorter than 

 the diameter of the disk, sub-equal ; flexuous, usually carried arching over 

 the margin. 



Mouth. Elevated on a blunt cone. 



Colour. 



Base. Edged wit h a narrow line of bright blue. 

 Column. Liver-brown. 

 Marginal Spherules. Brilliant azure. 

 Disk and Tentacles. Dull pellucid crimson. 

 Mouth. Rich crimson. 

 Gonidial Tubercles. Blue. 



Size. 



Large specimens sometimes cover with their base an area four inches 

 long by two wide, attain a height of about an inch, and expand to a 

 flower of three inches in diameter. 



Locality. 



The Mediterranean and Atlantic shores of Europe, universally distri- 

 buted, on exposed rocks, from half-tide, or even a higher level, to low- 

 water mark. 



Varieties. 



The characteristic colours of the species are crimson and green. The 

 extreme of variation on either hand is produced by either of these two 

 colours prevailing so as to exclude the other. But many intermediate 

 grades are found, either by the blending of the two hues into some inter- 

 mediate tint of olive, brown, or liver-colour, or else by the separation of 

 the two into a pattern of spots on a different ground, or, where the green 



