. Animal studies. 60 ANIMAL STUDIES blance which many of them show to animals in other groups. All the invertebrates, therefore, except the crabs and insects, were placed in one group until subsequent study made it possible to classify them more exactly. Ac- cording to the general shape of the body, and the arrange- ment of internal organs, worms are divided into a number of groups, chief among which are the fiatworms, the thread or roundworms, and the ringed worms or annelids. The Flatwoiois 53. Form and habitat.—The fiatworms, as their name indicates, are much flattened, leaf-like forms, som
. Animal studies. 60 ANIMAL STUDIES blance which many of them show to animals in other groups. All the invertebrates, therefore, except the crabs and insects, were placed in one group until subsequent study made it possible to classify them more exactly. Ac- cording to the general shape of the body, and the arrange- ment of internal organs, worms are divided into a number of groups, chief among which are the fiatworms, the thread or roundworms, and the ringed worms or annelids. The Flatwoiois 53. Form and habitat.—The fiatworms, as their name indicates, are much flattened, leaf-like forms, some species living in damp places on land, in fresh - water streams or ponds, or along the seacoast, while a variety of other spe- cies are parasitic. The free forms (Fig. 32) are usually small, barely reaching a length greater than five or seven cen- timeters (2 to 3 inches), but some of the parasitic species (Fig. 36) attain the great length of six to thirteen me- ters (20 to 40 feet). The free-living forms usu- ally occur on the under side of stones, and frequently are so delicate that a touch is sufficient to destroy them. A few Species are almost trans- Fig. , fresh-water flatworm (Ha- . ., , naria); B, marine flatworm t Lepto- parent, While many are COl- plana)_ Enlarged, from Nature. ored to harmonize completely with their surroundings, so that, even though fragile and defenseless, they escape the attacks of enemies by being overlooked. The night-time or dark days are their hunting. 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; Kellogg, Vernon L. [from old catalog].
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Keywords: ., bookauthorjordanda, bookcentury1900, bookdecade1900, bookyear1903
