. A textbook of invertebrate morphology [microform]. Invertebrates; Morphology (Animals); Invertébrés; Morphologie (Animaux). TYPE CliUSTACEA. 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 Sphreroma, lead a free existence, nevertheless there are certaiu parasitic forms. Thus the genera Oymothoa and yEj/rt are parasitic
. A textbook of invertebrate morphology [microform]. Invertebrates; Morphology (Animals); Invertébrés; Morphologie (Animaux). TYPE CliUSTACEA. 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 Sphreroma, lead a free existence, nevertheless there are certaiu parasitic forms. Thus the genera Oymothoa and yEj/rt are parasitic on the skin or in the mouth of fishes, but also retain the power of swimming and consequently are not much. Fig. ISQ.âAsellus communis. Diagram oi Structure, ab = abdominal appendages. I = liver-csecn. ao â aorta. mnp = uiaudibuliir palp. at^ = antennule. mrp = maxillipcd. at? = auteuna. r = rectum. ce = cerebral ganglion. « = stomach. c?i = chelate limb. t = thoracic appendage. ht = heart. vn = ventral nerve-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 unsymraetrical 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 appendages. â J n t»i« m i tv " ill I r, ji. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrat
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Keywords: ., bookcentury1800, bookdecade1890, bookpublishernewyo, bookyear1894
