. Zoology. Zoology. TEE BBACHIOPODa. 47 ciliated larva like that of the true worms, which after swim- ming about finally becomes fixed by a stalk to rocks. While in their development the Brachiopods recall the larvffi of the true worms, they resemble the adult worms in the general arrangement of the arms and viscera, though they lack the highly developed nervous system of the Anne- lids, as well as a vascular system, while the body is not jointed. On the other hand they are closely related to the Polyzoa, and it seems probable that the Brachiopods and. Fig. 50.—Lingulapyramidata with its sand-
. Zoology. Zoology. TEE BBACHIOPODa. 47 ciliated larva like that of the true worms, which after swim- ming about finally becomes fixed by a stalk to rocks. While in their development the Brachiopods recall the larvffi of the true worms, they resemble the adult worms in the general arrangement of the arms and viscera, though they lack the highly developed nervous system of the Anne- lids, as well as a vascular system, while the body is not jointed. On the other hand they are closely related to the Polyzoa, and it seems probable that the Brachiopods and. Fig. 50.—Lingulapyramidata with its sand-tube; natural size. Poh/zoa were derived from common low vermian ancestors, while the true Annelids probably sprang independently from a higher ancestry. They are also a generalized type, having some molluscan features, such as a bivalved shell, though having nothing homologous with the foot, the shell- gland or odontophore of mollusks. The class of Brachiopods is a very ancient one, nearly 2000 species of fossil Brachiopods being knoT^m. One living species of Lingula (Fig. 50) differs but slightly from the most ancient fossil species. It lives buried in the sand, where it forms a tube of sand around the stalk, just below low-water mark, extending from Chesapeake Bay to Florida. LiTERATUKE. A. Hancock. On the Oigauizalion of the Bracliiopoda. Phil. Trims. 1858. E. S. Morse. On llje Systematic Position of the Bracliiopoda. Proc. Boston Soc. Nat. Hist., xv. 1873. With the essays of Bioolvs. Lacaze-Duthiers, Kowalevsky. Dall, 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 Packard, A. S. (Alpheus Spring), 1839-1905. N. Y. , Holt
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