ZOOLOGY AND BOTANY, MICKOSCOl^Y, ETC. 811 



serving as food for plaice and eels, varies greatly from year to year, both 

 qnantitatively and qualitatively. The bottom animals are often eaten 

 up within the year ; the brood is in many cases far from ready to replace 

 what is devoured; diiferent species breed in different years. In Ahra 

 the breeding is about every second year, in Solen less frequently, in 

 My a triincata only at intervals of many years. The magnitude of 

 annual consumption in Thisted Bredning has varied between ,31 '8 and 

 84 '8 gr. gross vreight per square metre. The magnitude of the annual 

 production varied (1910-1915) between 42-1 and 77*1 gr. gross weight 

 per square metre. In Corhala, Mya trmuata^ and other bottom forms 

 it looks as if the growth continued throughout life. The general result 

 of the valuation studies is to show that an unlimited supply of fish food 

 is not available, and that transplantation of fry is profitable only 

 between certain limits, which in some cases have been alreadv surpassed. 



" J. A. T. 



Quantitative Estimate of Littoral Animals. — AV. A. Herdman 

 [Jouni. Liiiii. Sac. ZooJ., 1920, 34, 247-59, 8 figs.). The gregarious 

 Polych^et Sahellaria alveolata may show 65 to 75 tubes on a surface of 

 about 3 square inches. Taking 05, a square foot would have 3,120, a 

 square yard some 28,080. In many localities there are very many square 

 yards of SaheUaria, therefore many millions ; and these Polych^ets form 

 a favourite food of fishes like plaice and sole. A quarter of an inch 

 square is an average size for an adult of Balanus halanoides, and on one 

 square foot of rock near Port Erin 2,940 l^arnacles were counted. These 

 rock-barnacles are eaten by various animals, and their larvae form in 

 March and April an important part of the plankton. From 80 to 100 

 young mussels may be counted on a square inch, which means about 

 129,600 on a square yard, and there are very many such square yards 

 around our coast. " Xo doubt the majority of these young mussels 

 never grow to maturity. They are killed by storms, smothered by their 

 neighbours, or eaten by starfishes or by plaice and other fishes. In the 

 latter case they are not lost as a food matter, and even in the former 

 their remains will be eaten by something which will indirectly feed man. 

 Nothing is lost in the sea, and everything ultimately in the metabolic 

 cycle contributes to man's harvest." Of the small red Ascidian StyeJopsis 

 grossiUaria there may be 10 to 30 to the square inch, over 50,000 to 

 the square yard. Many other interesting records are given. J. A. T. 



Fauna of a Moor.— Adolf H^eberli {Rev. Suisse Zool., 1918, 26, 

 147-231, 18 figs.). An interesting account of the fauna of a moor near 

 Bern. The list shows 8 Flagellates (the commonest being Fhacus 

 longkaudatus and Peridinium tabidatum), 4 species of Ammba and 

 Pelomyxa linudeata, 30 Testacea, 5 Heliozoa, 28 CiUata, Hydra viri- 

 dissima, 6 Turbellarians, 3 Nematodes, 5 Oligocb^ets, 42 Rotifers, 

 6 Gastrotricha, the leech Helohdella staynalis, 2 Ostracods, 15 Copepods, 

 11 Cladocera, the Tardigrade Macrohiotus macronyx, 9 Hydracarina, the 

 bivalve Fisidium fossarium, the Gastropods Lymnsea peregra and 

 PlcmorUs nitidus, and various insect larvae such as Coretha 'plumicornis. 

 On many of the components of this characteristic fauna the author has 

 interesting; notes to make. 'I. A. T. 



