Text-book of comparative anatomy . to the protopodite, while the last tworepresent the joints of the endopodite. The feeler may here and there be wanting ;it is entirely wanting in the Cumacea (G). We see from the above review that among all Crustacea only the Ostracoda and 312 COMPARATIVE AX ATOMY CHAP. the Copepoda (more especially the latter) still retain in the structure of the man-dibles the original typical biramose form, since they alone retain the exopodite in theadult animal. d. The Anterior Maxillse (Fig. 212). These lie, in all Crustaceans, close to the mouth, and serve chieflyfor m
Text-book of comparative anatomy . to the protopodite, while the last tworepresent the joints of the endopodite. The feeler may here and there be wanting ;it is entirely wanting in the Cumacea (G). We see from the above review that among all Crustacea only the Ostracoda and 312 COMPARATIVE AX ATOMY CHAP. the Copepoda (more especially the latter) still retain in the structure of the man-dibles the original typical biramose form, since they alone retain the exopodite in theadult animal. d. The Anterior Maxillse (Fig. 212). These lie, in all Crustaceans, close to the mouth, and serve chieflyfor mastication, like the mandibles and the posterior maxilla?. Thebiramose character is much more commonly retained in them than inthe mandibles, the exopodite being more frequently present. Entomostraca. —Phyllopoda (D), the anterior maxillae are reduced to simpleunjoin ted masticatory ridges without feelers. In the Ostmcoda (B, C] also the mas-ticatory ridge is the principal part, but there is a feeler as well, and in the Cypridce. FIG. 212.—Anterior maxillae of various Crustaceans. A, Notodelphys agilis (after Brady).K, Cypridina stellifera (after Glaus). C, Cythera viridis (after Zenker). D, Daphnia similis(after Glaus). E, Euphausia pellucida, last Calyptopsis stage (after G. O. Sars). F, Astacusfluviatilis (after Huxley). G, Euphausia pellucida, adult (after G. O. Sars). //, Paranebalialongipes (after G. O. Sars). ex, Exopodite; en, endopodite ; A-, masticatory ridge; A-J, inner;to, outer masticatory ridge. and Gi/thcrid(c an exopodite, in the form of a fan-like plate, which is vibratile, andwhen the maxilla moves promotes respiration. The anterior maxillre of the free-living Copepoda (A) have masticatory ridges, feelers, and sometimes also fan-likeexopodites ; in the parasitic forms, on the contrary, these parts are much anterior maxillae of the Cirripcdia are simple masticatory ridges without feelers ;they are wanting in the Rhizocephala. Leptostraca. —The
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectanatomycomparative
