. The sea-beach at ebb-tide : a guide to the study of the seaweeds and the lower animal life found between tidemarks . Megalops,with large stalked eyes. Others are hatched as miniature names were given when the embryo stage was not recog-nized and the larvae were thought to be distinct species. The growth of the animal is effected by moulting. The Crus-tacea are named from the crust-like coveringwhich envelops them. It is a horny material,called chitin, in which are deposited particlesof carbonate of lime, making a rigid envelopwhich would prevent all freedom of motion,were it not
. The sea-beach at ebb-tide : a guide to the study of the seaweeds and the lower animal life found between tidemarks . Megalops,with large stalked eyes. Others are hatched as miniature names were given when the embryo stage was not recog-nized and the larvae were thought to be distinct species. The growth of the animal is effected by moulting. The Crus-tacea are named from the crust-like coveringwhich envelops them. It is a horny material,called chitin, in which are deposited particlesof carbonate of lime, making a rigid envelopwhich would prevent all freedom of motion,were it not that there are spaces free fromlime, and thus flexible joints are left. Whenthe animal expands it throws off this hardcovering and secretes a new and larger the time of moulting approaches, the oldcovering becomes loosened, and a delicatenew one is formed beneath it. The old shellsplits open across the back just behind thecarapace, and the soft animal withdraws first its cephalothoraxand then its abdomen, leaving the cover complete, including eventhe covering of the eyes and the lining of the stomach. The. Megalops stage of Cancerirroratus, just after changefrom zoea stage. CRUSTACEANS 249 new shell is rapidly hardened, being already formed when the oldone is cast, and the animal regains its normal condition in abouta week; in the meantime it is defenseless, and lies quiet in somesecluded place. Moulting is an exhausting process, and is attendedwith great dangers. A great mortality occurs at this time from ac-cidents, from weakness, and also from helplessness in case of hair-like processes scattered over the shell, often likefringes, are said to be organs of feeling. SUBCLASS ENTOMOSTRACA These are Crustacea of small, often microscopic size, of com-paratively simple organization, and with appendages adaptedto serve the purpose of respiration. These minute animalsmay be obtained by skimming the surface of the water witha muslin net, preferably at night, then w
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectmarinea, bookyear1901
