. iv. 8. Ill 



For by this position the claws are best suited for laying hold of 

 food and carrying it to the 'mouth. The distinction between the 

 Carabi and Carcini consists in the former having a tail while the 

 latter have none. For the Carabi swim about, and a tail is there- 

 fore of use to them, serving for their propulsion like the blade of 

 an oar. But it would be of no good to the Carcini ; for these 

 animals as a rule live close to shore, and creep into holes and 

 corners. In such of them as live out at sea, the feet are much 

 less adapted for crawling than in the rest, because they make but 

 little use of them for this purpose and depend for protection on 

 their shell-like covering. The Maiae and the crabs known as 

 Heracleotic are examples of this ; the legs- in the former being 

 very thin, in the latter very short.^ 



The very minute crabs, that are found at the bottom of the 

 net mixed with small fishes, have their posterior legs expanded 

 into the resemblance of fins or oar-blades, so as to help the animal 

 in swimming.^ The Carides are distinguished from the Carcinoid 

 species by the presence of a tail ; and from the Caraboids by the 

 absence of claws. This is explained by their large number of 

 feet, on which has been expended the material for the growth 

 of claws.* Their feet again are numerous to suit their mode of 

 progression, which is mainly by swimming.^ 



The parts on the ventral surface and near the head are in some 

 of these animals formed like gills, for the admission and discharge 

 of water. The parts lower down differ in the different sexes. For 

 in the female Carabi the parts are more laminar than in the males,^ 

 and in the female Crabs the flap is furnished with hairier appen- 

 dages. This gives ampler space for the disposal of the ova, which 

 the females retain in these parts instead of letting them go free, 

 like fishes and other animals, as soon as they are brought forth. 



In the Carabi and in the Carcini the right claw is invariably 

 the larger and the stronger.''^ For it is natural^ to every animal 

 to use its right side in preference to its left ; and nature, in dis- 

 tributing the organs, invariably assigns each, either exclusively 

 or in a more perfect condition, to such animals as can use it. So 

 is it with tusks, and teeth, and horns, and spurs, and all such 

 offensive and defensive weapons.^ 



In the Astaci alone it is a matter of chance which claw is the 

 larger, and this in either sex.^'' Claws they must have, because 

 they belong to a genus in which this is a constant character ;^^ 

 684 a. 



