. Animal activities : a first book in zoölogy. Zoology; Animal behavior. HOMOLOGIES AMONG CRUSTACEA. 109 frequently happens that animals bearing- onh' slight external resemblance to one another in adult life are classified together because in embryological life they show so man\' resem- blances. Among the ten thou- sand or more species of Crustacea, there are many strange forms which de- part from what might be called the typical crusta- cean structure. Compar- ing the common crab (Cancer irroratus) with the shrimp or crayfish, we notice the small size of the abdomen folded under the flattened
. Animal activities : a first book in zoölogy. Zoology; Animal behavior. HOMOLOGIES AMONG CRUSTACEA. 109 frequently happens that animals bearing- onh' slight external resemblance to one another in adult life are classified together because in embryological life they show so man\' resem- blances. Among the ten thou- sand or more species of Crustacea, there are many strange forms which de- part from what might be called the typical crusta- cean structure. Compar- ing the common crab (Cancer irroratus) with the shrimp or crayfish, we notice the small size of the abdomen folded under the flattened carapace. In the hermit crab the abdo- men is soft and has lost part of the swimmerets, be- cause of its habit of using the shell of a snail for pro- tection, }'et in the young the abdomen of this animal. Fig. 96. Water-flea {Daphnia pulex).. 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 French, Nathaniel S. (Nathaniel Stowers), 1854-. New York ; London : Longmans, Green, and Co.
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Keywords: ., bookcentury1900, bookdecade1900, booksubjecta, booksubjectzoology
