. A manual of zoology. Zoology. CRUSTACEA: AMPHIPODA 383 of body and in free thoracic segments. The epipodial plates are paralleled elsewhere only in carboniferous species, with which these forms apparently are closely allied. Legion III. Arthrostraca {Edriophlhalmala, Tetradccapoda). Although the Arthrostracan head consists of six segments, it is very short. It bears six pairs of appendages, one of the normal thoracic pair being added to it as Eyes, when present, are clusters of ocelli on the sides of the head. There are seven thoracic segments, the appendages of which are walki
. A manual of zoology. Zoology. CRUSTACEA: AMPHIPODA 383 of body and in free thoracic segments. The epipodial plates are paralleled elsewhere only in carboniferous species, with which these forms apparently are closely allied. Legion III. Arthrostraca {Edriophlhalmala, Tetradccapoda). Although the Arthrostracan head consists of six segments, it is very short. It bears six pairs of appendages, one of the normal thoracic pair being added to it as Eyes, when present, are clusters of ocelli on the sides of the head. There are seven thoracic segments, the appendages of which are walking feet without exopodites. The abdominal appendages, when present, are always biramous; the telson never bears appendages, and in the Amphipods is greatly reduced, sometimes being spht nearly its whole length. The nervous system (figs. 78, 409) is of the ladder type. The alimentary canal is straight and has an anterior enlargement, the chewing stomach, behind which empty one or more pairs of long liver. Fig. 409.—Male Orcheslia cavimana (after Nebeski). a', a~, antennEe; ao, aop, anterior and posterior aorUe; c, heart; d, digestive tract; ,§", brain and eye; h, testes; fe, gills; kf, maxilliped; I, liver; m, excretorj' organ and mandible; n, ventral nerve cord; o, rudimentary ovary; vd, vas deferens; I-VII, thoracic feet; 1-3, anterior, 4-6, pos- terior abdominal feet. tubes, while in a few Amphipods a pair of excretory tubes {m), the so-called Malpighian tubules, empty into the intestine near its end. Respiratory and circidatory systems vary so that they are best described in connec- tion with two orders. Order I. Amphipoda. The Amphipods are almost exclusively aquatic, a few species living on the shore near high-tide mark. A few live in fresh water {Gammancs* Allorchestes*), the majority being marine. On land they move by a. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appe
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectzoology, bookyear1912
