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MARINE INVERTEBRATES 



crabs of this species are very active and can swim rapidly. They also 

 have the habit of pushing themselves backward into the mud for con- 

 cealment. They are predaceous and pugnacious, and have great strength 

 in their claws, which they use with dexterity. They not only fight their 

 own kind, but show a bold front to all enemies, including man. The 

 average size is six inches across the carapace. 



GENUS Ovalipes 



O. ocellatiis (Rathbun), Platyonichus ocellatus (Latreille), 

 the lady-crab or sand-crab. A species common on sandy shores from 

 Cape Cod to Florida. It is found among the loose sands at low-water 

 mark, even on the most exposed beaches, and also is abundant on sandy 

 bottoms offshore. At low-water mark it buries itself up to the eyes 

 and antennae in the sand, where it watches for prey and foes, and quickly 



Ovalipes ocellatus, the lady-crab. 



disappears beneath the sand when danger approaches. It possesses the 

 power of burrowing in common with other marine animals which inhabit 

 exposed beaches of loose sand. By burying itself deep in the sand it is 

 protected from the action of the breakers. This species is easily dis- 

 tinguished by the color and shape of its carapace, taken in connection 

 with its posterior swimming-feet. The body is nearly as long as it is 

 broad, with five prominent spines on each side. The front margin is 

 indented on each side of a three-spined rostrum, to form cavities for the 

 eyes. The first limbs are large and have claws ; the posterior ones are 

 flattened into swimming-feet, and the intermediate three pairs are sim- 

 ple in structure, ending in points. In color it is white, covered with 

 spotted rings of red and purple. 



