A HISTORY OF LANCASHIRE pede. Somewhat later in the year these nauplii disappear and are succeeded by the ' Cypris ' stage of the same barnacle. The adult creatures resulting from this latter form then begin to settle down on all solid objects in the shallow water and they become a great nuisance to fishermen by encrusting the bottoms of their boats. Other crustacean larvas are the nauplii of cope- pods, and the zoea stages of the crabs Carci?7us, Portunus, and Cancer. About the end of March and the beginning of April diatoms appear in great abundance, the principal genera being Coscimdiscus, Biddulphia, Chato- ceros, and Rhizosolenia. After lasting for a month or so the diatoms become very scarce and towards midsummer may almost disappear from the tow-net gatherings. About this time of the year the gelatinous alga Halosphara viridis becomes very abundant. This form is always accompanied by a great mass of mucus which almost at once clogs up the meshes of the tow-nets and prevents the latter from 'fishing.' Another common constituent of the summer plankton is the flagellate Noctiluca miliaris, a common' cause of the phosphorescence of the water at this time and later in the year. Noctiluca is curiously restricted in its distribution. It appears in abundance all along the north Welsh, Cheshire, and Lancashire coasts in inshore waters, and it may reach out as far as the Liverpool N.W. and the Morecambe Bay light-ships; but it does not appear to get into Manx waters, nor is it common in the Firth of Clyde. Other flagellates are Ceratium tripos znAfurca, but these are not abundant. The ctenophores P leurobrachia and Beroe also appear in the summer, the former being at times especially abundant. The Larvacean tunicate Oikopleura occurs also in the summer and autumn. During the autumn months diatoms may again become abundant. Medusoids, the zoea and megalopa stages of crabs, and the larv£ of the shrimp also occur. Copepods and the ubiquitous Sagitta form the bulk of the plankton and last until the begin- ning of the winter. Then the abundance of the plankton undergoes decrease and copepods form its principal constituent. This general scarcity in mass and lack of variety in forms lasts during the colder winter months. SUMMARY OF LANCASHIRE AND IRISH SEA INVERTEBRATE ZOOLOGY PROTOZOA Two hundred and forty species of Foraminifera were recorded in the British Association List of 1896. Radiolaria and Infusoria are practically unworked, though both groups are abundantly represented. Quite recently the study of the parasitic Sporozoa has received much attention, and the following forms are recorded : Glugea {Nosema) /ophii, G. stephani, G. anomalum, Sphierospora platessa, and the remarkable Lymphocystis johnstonei. PORIFERA [Sponges) The sponges are fairly well known. Fifty-nine species were recorded in the B.A. List of 1896, of which five were new to science when first described in Lancashire waters. CCELENTERATA (Jelly-fish, sea anemones, etc.) Ninety-two species of Hydroids, 43 Hydromedusas, 2 Siphonophores, 4 Ctenophores, 3 Alcyonaria, and 22 Actinians, are recorded in the B.A. List. The strictly Lancashire forms constitute only a fraction of this list. All the Hydromedusas are, however, found in the inshore 1 But bv no means the exclusive cause. Occasionally when the water is phosphorescent the tow-nets may yield no organisms which are to be regarded as light-producing ones. In such cases the cause is no doubt some photogenous bacterium. 94
