1902. 



AND ANCIENT GEOGEAPHY. 



311 



Fig. 4. Distribution of the Crabs 

 of the subfamily TrichodactylineB. 



distinction of species seems to be very arbitrary within these 

 genera. Up to the present, about five or six species of Tricho- 

 dactylus and about fourteen species of Dilocarcinus have been de- 

 scribed. In the following we shall discuss them all together. 



The subfamily covers an area 

 that comprises the larger south- 

 ern half of Brazil (Bahia, Rio de 

 Janeiro, Goyaz, Minas Geraes, 

 S. Paulo, Sta. Catharina, Rio 

 Grande do Sul). It is found in 

 Paraguay, and in the Argentin- 

 ian provinces : Missiones, Chaco 

 and near La Plata (Ensenada). 1 

 Further, species of Trichodacty- 

 lineB are very abundant in the 

 Cordilleras, in the region of the 

 headwaters of the Amazonas 

 river, namely, in Bolivia (pro- 

 vince Beni, Yocuma river, be- 

 longing to the upper Madeira), in 

 Peru (rivers Ucayali, Huallaga), and in the Maranon at Nauta and 

 Loreto (Ecuador). Since there are also representatives known from 

 the lower Amazonas (Island Marajo), all these localities named seem 

 to form a continuous area, which extends from the Amazonas 

 river southward to La Plata, and from the Atlantic Ocean westward 

 over Brazil, Paraguay and Argentina to Bolivia and Peru, where it 

 reaches the eastern slopes of the Cordilleras. Apparently isolated 

 from this area, several species are found in Guyana, and, finally, one 

 species {Trichodactylus quinquedentatus Rthb.) is known from the 

 upper parts of the river Magdalena in Colombia, and from the 

 Escondido river in Nicaragua. 



It is quite possible that the isolated stations in Guyana, Colombia 

 and Nicaragua will be connected by subsequent discoveries 

 (Colombia is very near to the localities of the upper Amazonas), 

 and then we would have for this subfamily a continuous range, 

 which comprises the whole of South America southward to La 

 Plata, and from the Atlantic Ocean to the eastern slopes of the 

 Cordilleras, and which extends in Central America as far as 



1 I have received from the La Plata Museum specimens of Dilocarcinus 

 panoplus (Mrts.) from Ensenada. 



