PORTUMNUS. 43 



Gen. 13. PORTUMNUS, Leach. 



Tarsus of hind legs very wide, lanceolate. Carapace longer 

 than wide, and much contracted behind ; front with one of 

 the teeth on the middle line ; a single fissure on the upper 

 orbital margin. Abdomen of male with five segments. 

 Tarsus of second, third, and fourth pairs of legs narrow 

 and not adapted for swimming. 



Portumnus latipes, Penn. sp. Pennant's Swimming 

 Crab. — Carapace with the latero-anterior margins furnished 

 with very small teeth ; front legs short. It is of a dull 

 purplish-white, mottled with a darker hue. Pound on the 

 south and west coasts of England and on the Irish coasts. 

 In Scotland it has been found on the shores of the Pirth of 

 Porth and of the Moray Pirth. The Rev. G. Gordon re- 

 marks that it seems never to move so far from the land as 

 to become the prey of any of the more rapacious fish. 



Gen. 14. POLYBIUS, Leach. 



Carapace nearly circular, the legs all flattened ; the tarsi 

 of second, third, and fourth legs wide and lanceolate, those 

 of the fifth oval. 



The Rev. Alfred Norman informs me that he has seen 



