. Outlines of zoology. Zoology. SEGMENTED WORMS OK ANNELIDA. having been compared to the notochord of Vertebrates. The sexes are usually separate, the reproductive organs simple and devoid of accessory structures. The nephridia function as genital ducts. There is a metamorphosis in development. (a) .Some of these marine Polychaites lead a free and more or less active life, crawling between tidemarks or on the sea bottom, burrowing in the sand, or swimming in the open water. These Errantia have well- developed appendages, and a large pre-oral segment, and are generally furnished with eyes and w
. Outlines of zoology. Zoology. SEGMENTED WORMS OK ANNELIDA. having been compared to the notochord of Vertebrates. The sexes are usually separate, the reproductive organs simple and devoid of accessory structures. The nephridia function as genital ducts. There is a metamorphosis in development. (a) .Some of these marine Polychaites lead a free and more or less active life, crawling between tidemarks or on the sea bottom, burrowing in the sand, or swimming in the open water. These Errantia have well- developed appendages, and a large pre-oral segment, and are generally furnished with eyes and well-developed antennce. Gills are usually associated with the dorsal parts of the parapodia. Most of them feed on other animals, and have sharp "horny jaws," while the anterior part of the gut is protrusible as a proboscis. Nej-eis and Ncphthy^ are two common genera, species of which may be unearthed by digging in the sand close to rocks, though at times these or other species are seen swimming freely. The sea mouse, Aph) otrite, has irridescent bristles, a feltwork of matted hair covering large gill plates which lie along its back, a very large muscular , and a gut with numerous irregular branches extending throughout the body. A very common shore form, a little like a small Aphrodile, is Polynoe. As an actively errant worm, with well developed eyes, AUiope may be noted, and the family of Syllida; is re- markable for the unusually prolific asexual budding, which sometimes results in a chain or even an irregular branched aggregate of individuals. As the cuticle is often irridescent, and as the red blood ]iiay shine through tlie skin, these marine worms are frequently beautiful. The list of nymjihs and goddesses has been the source of such titles as Nereis^ Aph?oditt\ Eunice^ and Hcniiione^ and one can almost believe the legend, according to which a specialist on Errantia christened his daughters after his seven favourites. [b) Other marine Polycha^ta, however,
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1895
