PODOPHTHALMIA. 



63 



Fig. 78. — Platyonichus ocellatus, lady crab, natural size. 



As examples of the swimming crabs we may mention tlie " Green Cra^," Carcinus ■ 

 moenas, which has a peculiar distribution, occurring on our coasts only from Cape Cod 

 to Maryland, and on the European from Finmark down through the Mediterranean 

 into the Black Sea. Besides these, its regular habitat, it has been reported from 

 Brazil, Panama, the Sandwich 

 Islands, and India. With 

 its restricted distribution on 

 our own coast, this wide dis- 

 tribution over the globe is of 

 peculiar interest. Another 

 of the swimming crabs, the 

 Neptunus hastatus, furnishes 

 the soft-shelled crab so well 

 known to epicures. This 

 crab, which extends along 

 our Atlantic coast from Mas- 

 sachusetts to Florida, buries 

 itself in the sand, exposing 

 only its eyes and antennae. 

 Like all of the Crustacea, it 

 sheds its shell, and just after 

 the moult it forms the delicacy 

 of the table, the integument 

 not then being hardened. At 

 the time of moulting the flesh is hard, but in a few hours it becomes soft and watery, 

 and then is of inferior quality. Only a few days are requii'ed to bring the new skin 

 to its former consistency. Our figure of the lady crab, a beautiful species covered 

 with rings of red and purple, will sufficiently illustrate the characters of the Portunidse, 

 while the development is shown in figures 5, 6, 13, and 14, which represent the various 

 stages of young of the soft-shelled crab mentioned above. 



The remaining divi- 

 sion of the Decapoda, 

 the OCYPODOIDEA 

 or Catometopa, are the 

 highest, both as shown 

 by structure and by em- 

 bryology. The anten- 

 nulse are transverse, the 

 .fourth joint of the ex- 

 ternal maxillipeds artic- 

 ulates with the apex or 

 outer angle of the third ; 

 the body is broad, and, 

 in the higher groups, 

 quadrate in outline ; the 

 epistome is very short 

 and the male genital organs show a complication not found in other groups. In divid- 

 ing the group into families authors show a considerable diversity of opinion, as the 



Fig. 79. — Geryon tridens, from deep water, North Atlantic Ocean. 



