. The doctrine of descent and Darwinism. Evolution. TYPES AND FAMILIES. 31 arranged radially round an axis, passing through the dorsal and ventral pole. The cavity, which in most other animals—for instance, in man—is termed the abdominal cavity, the space between the intestinal wall and the abdominal parietes, is deficient in them ; but, on the other hand, from the stomach proceed in general various kinds of tubes and branchia, which to a certain extent replace the abdominal cavity. P'ig. 2 represents a. Medusa, Tiaropsis Diadema, after Agassiz. The darkly- shaded organs form the so-called coe

- Image ID: RCC8YR
. The doctrine of descent and Darwinism. Evolution. TYPES AND FAMILIES. 31 arranged radially round an axis, passing through the dorsal and ventral pole. The cavity, which in most other animals—for instance, in man—is termed the abdominal cavity, the space between the intestinal wall and the abdominal parietes, is deficient in them ; but, on the other hand, from the stomach proceed in general various kinds of tubes and branchia, which to a certain extent replace the abdominal cavity. P'ig. 2 represents a. Medusa, Tiaropsis Diadema, after Agassiz. The darkly- shaded organs form the so-called coe
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Image ID: RCC8YR
. The doctrine of descent and Darwinism. Evolution. TYPES AND FAMILIES. 31 arranged radially round an axis, passing through the dorsal and ventral pole. The cavity, which in most other animals—for instance, in man—is termed the abdominal cavity, the space between the intestinal wall and the abdominal parietes, is deficient in them ; but, on the other hand, from the stomach proceed in general various kinds of tubes and branchia, which to a certain extent replace the abdominal cavity. P'ig. 2 represents a. Medusa, Tiaropsis Diadema, after Agassiz. The darkly- shaded organs form the so-called coelenteric apparatus. Of the Echinoderms, the reader is probably ac- quainted, at least with the star-fish (Asterias) and the sea-urchin (Echinus), of which the general form is like- wise usually radiate. Besides a peculiar chalky deposit, or greater or less calcification of the skin covering, a system of water-canals forms a characteristic of this family. With these are connected the rows of suckers, which, by protrusion and retraction, serve as organs of locomotion. On account of the radiate structure pre- vailing among the Echinoderms, Medusae, and Polypes,. 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 work.. Schmidt, Dr. (Eduard Oskar), 1823-1886. London, H. S. King & Co.

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