. Text book of zoology. Zoology. Sub-Glass 1. Entomostraca. Order 6. Copepoda, 203 is a sac without limbs (Pig. 165 C), and with only two longer or shorter (often thread-like) egg-sacs. It is immovably attached to the host, in some cases by means of the second antennee, the second maxillae or the maxillipeds modified into long arms; in others by means of the whole front part of the animal, whic-h is imbedded in the body of the host. The males of the more strongly modified forms are usually pigmy, attain only a small fraction of the size of the females, and as a rule are attached to them in the
. Text book of zoology. Zoology. Sub-Glass 1. Entomostraca. Order 6. Copepoda, 203 is a sac without limbs (Pig. 165 C), and with only two longer or shorter (often thread-like) egg-sacs. It is immovably attached to the host, in some cases by means of the second antennee, the second maxillae or the maxillipeds modified into long arms; in others by means of the whole front part of the animal, whic-h is imbedded in the body of the host. The males of the more strongly modified forms are usually pigmy, attain only a small fraction of the size of the females, and as a rule are attached to them in the neighbourhood of the genital aperture; they are not usually so entirely modified as the females may be, as a rule they have several pairs of limbs, etc. The parasitic Copepods, like the free-living ones, are hatched as nauplii, which swim freely about, and after some moults reach a state like that of the free-living adult. The parasites owe their ultimate deformity to a "retrograde metamorphosis " occurring after fixation. In some parasitic Crustacea, , Lernsea hranchialis, living on the gills of tlie Cod, the male and female are fairly alike up to the time of copulation, presenting a tolerahly normal copepod form ; after pairing, however, the female grows con- siderably, and becomes quite distorted, whilst the male perishes; wherefore no male is found with the adult female Lernsea. Order 7. Cirripedia. The Cirripeds are furnished with a sort of protecting shield, the so-called mantle, which is attached to the rest of the animal only Fig. 166. Fig. oa- Fig. 166. Lepas. The right half of the mantle is removed, the body shown in longi- tudinal section.—^After Claua. Fig. 167. Balanus. The right half of the mantle and shell taken away.—After Darwin. a and b the paired valves of the mantle, u scutnm, b tergum, c unpaired dorsal valve, carina. Oj anterior antennae, an anus, h cement gland, I liver, m adductor muscle of mantle, m' retractor muscle, o' female
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1896
