. A manual of zoology. Zoology. /. CRUSTACEA. 413 either suppressed or, as is easily shown, the corresponding stages are passed in the egg. Two of the larval stages are especially im- portant, the nauplius and tlie zoea. The ncmplius (figs. 7, 439) consists of three segments covered by a dorsal shield and bearing below three pairs of appendages. The first -pah, developing later to the first antennje, are simple; the others, corresponding to the. Fig. —Zoea of Carcinu& mcenan. (After Faxon.) cephalic appendages. 7i, heart; t, intestine; I-VII, second antennas and mandibles, are schizop
. A manual of zoology. Zoology. /. CRUSTACEA. 413 either suppressed or, as is easily shown, the corresponding stages are passed in the egg. Two of the larval stages are especially im- portant, the nauplius and tlie zoea. The ncmplius (figs. 7, 439) consists of three segments covered by a dorsal shield and bearing below three pairs of appendages. The first -pah, developing later to the first antennje, are simple; the others, corresponding to the. Fig. —Zoea of Carcinu& mcenan. (After Faxon.) cephalic appendages. 7i, heart; t, intestine; I-VII, second antennas and mandibles, are schizopodal. Internally there is a three-chambered alimentary tract, a suprauesoj^hageal ganglion on which is an unpaired eye, and a ventral chain. The naujjlius is almost universal among the lower Crustacea, and some writers believe that it represents an ancestral form from which the Crus- tacea have descended, a view open to much objection. The zoea is more complex. It consists (fig. 415) of cephalo- thorax and abdomen, the latter without appendages, the former. 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. New York, H. Holt and Company
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectzoology, bookyear1902
