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The Descent of Man

The Descent of Man

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ting a partner, or for the individuals <strong>of</strong> the same<br />

sex to struggle together in rivalry.<br />

SUB-KINGDOM OF THE ARTHROPODA:<br />

CLASS, CRUSTACEA.<br />

In this great class we first meet with undoubted<br />

secondary sexual characters, <strong>of</strong>ten developed in<br />

a remarkable manner. Unfortunately the habits<br />

<strong>of</strong> crustaceans are very imperfectly known, and<br />

we cannot explain the uses <strong>of</strong> many structures<br />

peculiar to one sex. With the lower parasitic<br />

species the males are <strong>of</strong> small size, and they<br />

alone are furnished with perfect swimminglegs,<br />

antennae and sense-organs; the females<br />

being destitute <strong>of</strong> these organs, with their bodies<br />

<strong>of</strong>ten consisting <strong>of</strong> a mere distorted mass.<br />

But these extraordinary differences between the<br />

two sexes are no doubt related to their widely<br />

different habits <strong>of</strong> life, and consequently do not<br />

concern us. In various crustaceans, belonging to<br />

distinct families, the anterior antennae are fur-

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