422 E. .1. ALLKN AND E. W. NEL80N. 



Cucumaria saxicola. — A female Cue urn aria, one of a 

 number in a dish containing "outside" water, laid eggs, 

 which were fertilised, and segmented on May 12th, 1906. A 

 number of these were placed in a flask in 800 c.c. of " outside" 

 water, which had been sterilised by heating and then treated 

 with animal charcoal and filtered. About 1 c.c. of fine 

 plankton, containing diatoms, was added to the flask on May 

 12th. On May 25th some of the water was poured off and a 

 new supply added. As the amount of food seemed small, some 

 culture of a green alga (Pleurococcus mucosus [Kutz.] 

 Rabenh.) was added, and this continued to grow well in the 

 flask. The larvte continued healthy and formed young 

 Cucumaria, of which mauy were still alive ou July 25th, 

 1907, i.e. fourteen months after fertilisation. Some of the 

 water was changed in this flask on May 30th, 1906, June 

 18th, 1906, and September 15th, 1906, and July 25th, 1907. 

 Although many of these Cucumaria remained quite healthy 

 they did not grow to any great size. Probably the food 

 which was suitable to the larva3 and early stages, ought to 

 have been changed as the animals grew older. 



Pomatoceras triqueter. — The larva3 of Pomatoceras 

 are perhaps the easiest to rear, and give the most certain 

 results of any with which we have experimented. They do 

 well on the minute variety of Nitzschia closterium, but 

 will feed upon almost any small diatom. Since the adults live 

 in calcareous tubes attached to stones, and the tubes have to 

 be broken open before the eggs can be obtained, it is not easy 

 to get the latter free from infection of other organisms. If, 

 therefore, the eggs are fertilised and placed in sterilised 

 animal - charcoal water with only moderate precautions, 

 sufficient growth of diatoms or other organisms will generally 

 take place in the jar to feed the larvae and bring them to the 

 adult state. When once fixed to the glass the worms are very 

 hardy and healthy, and a stream of ordinary aquarium water 

 can be run through the jar. They then grow rapidly and 

 attain a size equal to any found on the shore. The following 

 experiment may be given in detail to illustrate the time 



