. Animal forms; a second book of zoology. Zoology. 68 ANIMAL FORMS m to the belief that the ancestors of some of these animals were segmented worms whose present condition has arisen possibly in accordance with their sluggish habits. This view is strengthened by the fact that in a very few species the larvae are dis- tinctly segmented, but lose this char- acter in becoming adult. As before mentioned, the greater number of species live in bur- rows in the sand or crevices in the rocks, from which they reach out and gather in large quantities of sand. As these substances Fig. 42.—A gephyrea
. Animal forms; a second book of zoology. Zoology. 68 ANIMAL FORMS m to the belief that the ancestors of some of these animals were segmented worms whose present condition has arisen possibly in accordance with their sluggish habits. This view is strengthened by the fact that in a very few species the larvae are dis- tinctly segmented, but lose this char- acter in becoming adult. As before mentioned, the greater number of species live in bur- rows in the sand or crevices in the rocks, from which they reach out and gather in large quantities of sand. As these substances Fig. 42.—A gephyrean worm (Dendrostoma). Specimen pass down the in- on left opened to show Jc, kidney, m, muscle bands, . i • . i , • and nerve-cord. testme the nutn' . tive matters are di- gested and absorbed, while the indigestible matters are voided to the exterior. When large numbers are associated together they are doubtless important agents in modifying the character of the sea bottom, thus acting like the earth- worms and their relatives. 71. The sea-mats (Polyzoa).—The sea-mats or Polyzoa constitute a very extensive group of animals common on the rocks and plants along the seashore, and frequently seen in similar situations in fresh-water streams. A few lead lives as solitary individuals, but in the greater number of species the original single animal branches many times, giving rise to extensive colonies. In some species these extend as low encrusting sheets over the objects on which they rest; while in others the branches extend into the. 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 Jordan, David Starr, 1851-1931; Heath, Harold, 1868- [from old catalog] joint author. New York, D. Appleton and company
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectzoology, bookyear1902
