. The sea-beach at ebb-tide : a guide to the study of the seaweeds and the lower animal life found between tidemarks . pairs of appendages are grouped about the are the mandibles, the maxillce, and the maxiUipeds. Themandibles are at the mouth-opening, and, being heavy and hard,are adapted to tearing and grinding; they have a jointed attach-ment, the palpus, whose office is to keep the mandibles two pairs of maxilla? are delicate and leaf-like. The threepairs of maxillipeds grow gradually larger, the last pair beingvery prominent and extending over the other mouth-parts. N
. The sea-beach at ebb-tide : a guide to the study of the seaweeds and the lower animal life found between tidemarks . pairs of appendages are grouped about the are the mandibles, the maxillce, and the maxiUipeds. Themandibles are at the mouth-opening, and, being heavy and hard,are adapted to tearing and grinding; they have a jointed attach-ment, the palpus, whose office is to keep the mandibles two pairs of maxilla? are delicate and leaf-like. The threepairs of maxillipeds grow gradually larger, the last pair beingvery prominent and extending over the other mouth-parts. Nextcome five pairs of walking-feet. One or more pairs of these feethave pincer-like ends, or claws. Some species have the claws im-mensely developed, as in lobsters. The claws are the chelce, andthe feet which bear the chelse are termed the cJielipeds. The restof the walking-feet have generally single, hook-like ends, but arevariously modified in different species. The abdominal segmentshave six pairs of appendages, also variously modified. The lastsegment is without appendages, but often is extended into a tail,. ILATK I A. External Anatomy of a Lobster. (. carapace; e, eye; i|id-dite; s. rxopoditi-: I-VII, iilidoininal sc^incnts: 1, aiitciiiuila; 2. :iu-trrma: It. niandihlcs; 4, 5, maxillic ; (i. 7. H, imixilii|niU ; !l. lii^ pi10-Kl, walking- SHRIMPS AND PRAWNS 259 or fin-like expansion. The next to the last segment, in many forms,lias appendages modified into swimming-plates, which extend oneach side of the telson, forming a broad, fan-like caudal extremity. They have, then, to correspond to the twenty segments of thebody, two pairs of sensory, six pairs of mouth-, and five pairs ofwalking-appendages attached to the cephalothorax, and six pairson the abdomen. The terminal segment, or telson, is without ap-pendages. The exopodite is present on the maxillipeds, but dis-appears from the walking-feet in the higher forms. In moulting the Mtu-i-in-a split in the longitudinal line
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectmarinea, bookyear1901
