. A manual of zoology. Zoology. I. CRUSTACEA 361 usually the abdominal feet and the mouth-parts retain the two-branched condi- tion. Embryology further shows that even in the crabs all the feet are at first schizopodal and that the walking legs lose the exopodite during growth. There is evidence to show that the schizopodal foot is not the primitive type. This is furnished by the phyllopod foot (fig. 375, 77), wdiich consists of a median axis, b, bearing on the inside six cnditcs, i, and on the outer side two exiles, a Jlabcllum or epipodile, a, and a gill, k. This furnishes the schizopodal fo
. A manual of zoology. Zoology. I. CRUSTACEA 361 usually the abdominal feet and the mouth-parts retain the two-branched condi- tion. Embryology further shows that even in the crabs all the feet are at first schizopodal and that the walking legs lose the exopodite during growth. There is evidence to show that the schizopodal foot is not the primitive type. This is furnished by the phyllopod foot (fig. 375, 77), wdiich consists of a median axis, b, bearing on the inside six cnditcs, i, and on the outer side two exiles, a Jlabcllum or epipodile, a, and a gill, k. This furnishes the schizopodal form by a loss of the four basal endites (those nearest b) and the development of the two terminal endites into exopodite and endopodite. Still the schizopodal condition is so nearly universal among Crustacea that it must be accorded great weight in classification. The appendages furnish a further diagnostic character in that two pairs of antenn;e are present in the Crustacea (see, however, Triloljita-). Antenn;e, it will be remembered, are preoral appendages innervated from the brain. In some cases, as many Entomostraca, the second pair may lose their sensory functions and Ijecome mere swimming Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Hertwig, Richard, 1850-1937; Kingsley, J. S. (John Sterling), 1854-1929, ed. and tr. New York, H. Holt
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectzoology, bookyear1912
