70 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



calculated that the Sardine takes as a meal about 

 20,000,000 of the small Ceratium tripos shown in fig. I. 

 at 2 ; while Professor Hensen has found 130 millions of 

 them in 10 cubic metres of water from the Baltic. This 

 and other kinds of Ceratium (1 and 3) are one of the chief 

 causes of the luminosity or " phosphorescence " of the sea. 

 Another little Protozoon which frequently causes the sea 

 to sparkle with light in the night is Noctiluca miliaris (fig. 

 I., 5), which is occasionally present in great abundance in 

 the Irish Sea. These all swim on the surface of the sea, 

 but there are many other Protozoa which have heavy 

 shells, and are usually found on the bottom or attached 

 to other objects. A good example of this is Rotalia 

 beccarii seen at 4, and belonging to the Foraminifera. In 

 some parts of the world Foraminifera are so abundant that 

 their minute limy shells accumulate as enormous deposits 

 covering many million square miles of the floor of the 

 ocean, and those that existed in former times now build 

 up mountain ranges in some parts of the world. There 

 are other Protozoa occasionally seen at the seaside, such 

 as Folliculina ampulla (No. 6), enclosed in a delicate shell 

 and protruding its soft body, bearing a fringe of numerous 

 delicate hair-like filaments, by the lashing of which food 

 particles are wafted to the mouth ; and Tintinnus 

 campanula (No. 7), a somewhat similar form, which floats 

 in the sea and can be captured by a fine muslin net. 



There is a group of microscopic plants, the Diatoms, 

 which is worthy of attention because of its great import- 

 ance as a food of animals. Diatoms are unicellular Algse, 

 and a few of the commoner forms are shown in the figure : 

 8 is a Biddulphia, 9 a Coscino discus, 10 is Chaetoceras 

 secundum, and 11 Bacteria strum varians. 



Fully detailed reports upon the Foraminifera of our 

 district by Mr. Siddall and others, and upon the Diatoms 



