Synopsis
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1874 Excerpt: ...and physiology is typical of the arthropod division of the sub-kingdom Annulosa. The arthropoda comprise the four classes, myriapoda, insecta, arachnida, and Crustacea, all characterised by the possession of jointed body appendages. To the latter class the lobster belongs. 175. Morphology.--It is observed that this animal also is provided with an exoskeleton, but one very different, indeed, from what we have observed in anodon. The "crust" or hard part in the lobster contains twenty segments. Hence the body may be regarded as consisting of twenty somites, each "somite" being formed of a body part, with its appendages. Of these somites, six form the abdominal region (fig. 85), with the tail or telson e, which is not regarded as one of the body segments. They differ from the somites of the rest of the body in being articulated to, and hence movable upon, each other, by means of a flexible portion of the external integument h, and also in the form of the appendages. If we take one of the abdominal rings and examine it, we shall observe that its transverse section will be somewhat like the accompanying figure (fig. 86). The arterial blood system is observed to be 1 near the dorsal side of the animal, the ganglionic cords or nerves are near the opposite side, while the viscera lie in the cavity between. The upper part of the circumference of the ring Fig.85.--BoDYSKElE-is called the tergum, the under part Ton Of Lobster, the sternum, and the part where both detaohedaSXett TMite at «P anSle » termed the order, a, Rostrum pleuron. Each segment is provided or beak; b, cervical with a pair of appendages, planted suture; c, carapace; in sockets g, h, k, the basal part of rings e ST? eaoh, 9, S termed a basipodite or a, 'flappers;"' ...
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