ALCYONIUM. i)7 



and other genera belonging to the Alcyonaria. The 

 colonies which grow on worm tubes seem to require a 

 broader base than the others, and several specimens have 

 been obtained which appear to be mainly encrusting 

 plates, the vertical growth being relatively very slight. 

 The specimens which grow on rocks, on the other hand, 

 usually exhibit a much narrower base of support, grow 

 rapidly in height and branch earlier and more freely than 

 others. 



The colour is usually pale flesh-colour when the colony 

 is fresh, but this soon fades in an aquarium, and the 

 colony becomes white. Many freshly-caught colonies 

 from Plymouth Harbour were quite pale when brought 

 into the laboratory, but perhaps their conditions of life 

 were not perfectly healthy. A yellow variety of several 

 tints is frequently found. I have obtained specimens of 

 it from the West Coast of Scotland, Port Erin, Puffin 

 Island, the Bristol Channel and elsewhere. This colour 

 is due to a fixed pigment in the spicules, and it shows no 

 appreciable change after years of immersion in spirit 

 At Port Erin there are two distinct tints of the yellow 

 variety recognised, the one paler and the other a deep 

 orange. I do not think that a red colour in the spicules 

 ever occurs in this ,species. The red Alcyonium dis- 

 covered by Couch off the coast of Scotland is Alcyonium 

 glomeratum of Hassall, and is distinct from A. digitatum, 

 Linn, in various respects. 



Reproduction. 



Alcyonium, digitatum is always dioecious. No herma- 

 phrodite colonies have yet been observed. The eggs, 

 when ripe, are of a yellowish-red colour, and are dis- 

 charged into the water by the mouths of the polyps 

 which bear them. At the same time of the year 



G 



