. A text-book of invertebrate morphology. Invertebrates. TYPE GBU8TAGBA. 415 forwards only a short distance into the thorax segment. It possesses one or two pairs of ostia and is closed' behind, giving off in front and at the sides numerous aortse. A shell- gland has been observed in some Isopoda, but the antennary gland is wanting. Although the majority of the marine forms, such as Idotea and Sphceroma, lead a free existence, nevertheless there are certain parasitic forms. Thus the genera Gymothoa and ^ga are parasitic on the skin or in the mouth of fishes, but also retain the power of swimmi
. A text-book of invertebrate morphology. Invertebrates. TYPE GBU8TAGBA. 415 forwards only a short distance into the thorax segment. It possesses one or two pairs of ostia and is closed' behind, giving off in front and at the sides numerous aortse. A shell- gland has been observed in some Isopoda, but the antennary gland is wanting. Although the majority of the marine forms, such as Idotea and Sphceroma, lead a free existence, nevertheless there are certain parasitic forms. Thus the genera Gymothoa and ^ga are parasitic on the skin or in the mouth of fishes, but also retain the power of swimming and consequently are not much 1 1 lit. Figs. 189.âAsellus communis. Diagram of Structure. «J = abdominal appendages. I = liver-cseca. ao = aorta. '"â np = maudibular palp. afi = antennule. mxp = maxilliped. aP = antenna. 'â = rectum. ce = cerebral ganglion. s = stomach. ch = chelate limb. t = thoracic appendage. ht = heart. i>n = ventral neive-cord. modified. The genus Bopyrus, which lives in the branchial cavity of shrimps, becomes in the female somewhat distorted in shape and asymmetrical, and the mouth-parts become transformed into a suctorial proboscis and the eyes disap- pear. The male, however, which is much smaller than the female, retains the eyes and does not depart from the usual symmetrical body form. The degeneration of the female proceeds much farther in the genus Entoniscus, which lives either partly or wholly included within the body-cavity of other Crustacea and assumes a saclike unsymmetrical form, recalling to a certain extent that of some of the parasitic Copepoda. At the time of pairing both sexes are alike fully segmented and with an almost full complement of 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 McMurrich, J. Playfair (James Playfair), 1859-1939.
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Keywords: ., bookcentury1800, bookdecade1890, bookpublishernewyo, bookyear1894
