. Outlines of zoology. Zoology. BRACHIOPODA. (a) Tentacles in a crescent—Fresh water, Cristate/la, Lophopiis, etc. {b) Tentacles in a circle—Marine, except Paludicella; Flustra, the common sea-mat; Membranipora, encrusting sea-weed, etc.; Cellepora, very calcareous ; Alcyonidium, gelatinous. The Entoprocta include the colonial Pedicellina, with a few allied genera, also the non-colonial Loxosoma, in which the buds separate as soon as they are formed. All the forms are stalked and minute. The anus is included within the tentacular circle. In the metamorphosis of Pedicellina there is an elongati
. Outlines of zoology. Zoology. BRACHIOPODA. (a) Tentacles in a crescent—Fresh water, Cristate/la, Lophopiis, etc. {b) Tentacles in a circle—Marine, except Paludicella; Flustra, the common sea-mat; Membranipora, encrusting sea-weed, etc.; Cellepora, very calcareous ; Alcyonidium, gelatinous. The Entoprocta include the colonial Pedicellina, with a few allied genera, also the non-colonial Loxosoma, in which the buds separate as soon as they are formed. All the forms are stalked and minute. The anus is included within the tentacular circle. In the metamorphosis of Pedicellina there is an elongation of the dorsal region of the body, and a consequent approximation of the mouth and anus on the shortened ventral surface. There is no apparent body cavity in the adult, and the mesoderm arises from two primitive mesoblasts. The nephridia are anterior, minute, and do not serve as genital ducts, but resemble the "head kidneys" of Annelid trochospheres. They are said to terminate in flame cells like those of Platyhelminths. In all these three respects the Entoprocta differ from the Ectoprocta, and from the JSIolluscoidea generally; but the signifi- cance of this is uncertain. Class Brachiopoda. The Brachiopods or Lamp-shells are quaint marine animals, once very numer- ous, but now decadent. The body is enveloped dorsally and vent rally by two folds of skin or mantle; these secrete a shell, usually of lime, but sometimes organic. The development of this shell has apparently modified both the position and the relations of the organs. There is no real resemblance between a Brachio- pod shell and that of a bivalve Mollusc, except that both consist of two valves. dorsally and ventrally ; in Lamellibranchs they are lateral; moreover, in Brachiopods the ventral valve is usually the larger. It is hardly necessary to say that the Brachiopod organism is not the least like a Mollusc. A considerable part of the space between the valves of the shell is filled up by two long &qu
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Keywords: ., bookauthorth, bookcentury1800, bookdecade1890, booksubjectzoology
