INVERTEBRATE BOTTOM FAUNA 



463 



Laomcdea flex2wsa, and Clava squamata (see Fig. 321). There 

 are several bryozoans ^ here too, and the fucoids are often densely 

 thronged by small white spiral-shaped tube-worms [Spirorbis). 

 Amongst the un- 

 attached forms as- 

 sociated with the 

 algae I may mention : 

 Littorina obtusata, 

 which keeps mostly 

 to little bays shel- 

 tered from the action 

 of the waves ; L. 

 littorea, which is very 

 common ; and our 

 smallest shelled snail 

 Skene a planorbis, 

 which is met with in 

 favoured spots under 

 stones and upon algae 

 of different species. 



More local in 

 their occurrence, 

 though generally numerous 

 of Actiniae 



Fig. 320. 

 Dynamena pmnila, L. (After Hincks. 



where found, are certain species 

 the red Actinia equina (see Fig. 322), the yellow 

 or brownish MetiHdiuvi dianthus (see Fig. 

 323), and Urticina crassicornis being the 

 commonest forms. The first of these is 

 generally found in quiet bays where the 

 shore is covered with large stones and 

 pebbles, the individuals being sometimes 

 attached to these and sometimes to cracks 

 in the rock. As this species produces its 

 young fully developed, and the newly-born 

 actiniae are able to attach themselves easily, 

 it is frequently met with in fairly large 

 colonies. 



Another remarkable mode of propaga- 

 tion, namely schizogony, is to be seen in Metridium diantJms 

 in its younger stages. From the foot-disc of the animal small 

 pieces unwind and form new organs, such as new tentacles, new 

 mouth, etc. In this way colonies are formed, which may be 

 widely distributed over the rock or the roots of the laminaria. 



^ Chiefly Alcyonidiuin hirsiitum, Fliistrella hispida, Bowerbankia i?/ibricata. 



Fig. 321. 



Clava squamata, Miill. 

 (After Hincks.) 



