306 ORTMANN — DISTRIBUTION OF DECAPODS [April 3, 



gendorf, 1898, p 23) and Somali country (de Man, 1898, 



p. 270). 

 D. mitis Hlgdf. (1898, p. 24). German East Africa and British 



East Africa (Mombas). 

 D. alluaudi A. M.-E. and Bouv. (= cristata Rthb.). Seychelle 



Islands. 



The Deckeniince are, as is expressed by their morphological char- 

 acters (Ortmann, 1897, p. 297), a highly specialized group of the 

 family which may be connected without hesitation with the genus 

 Potamon, and possibly with the African branch of it. This sub- 

 family is a group localized in East Africa, and the presence of one 

 of the species in the Seychelles indicates a former connection of 

 these islands with East Africa. It is quite probable that this con- 

 nection is an additional proof for that old Afro-Indian landbridge 

 discussed above, which included Madagascar (see No. 5, p. 295 , 

 and No. 1, p. 305). 



3. Subfamily : Potamocarcininee. 



The subfamily Potamocarcinince (= Pseudothelphusince) is re- 

 stricted to America and is wanting in the Old World. The syste- 

 matic arrangement of it is a matter of discussion, since the two 

 revisions published by Rathbun and Ortmann do not agree as to the 

 principles of division. 



Regarding the subfamily as a whole, its range comprises the 

 following parts : West Indies — Greater Antilles : Cuba (including 

 the Isle of Pines), Hayti, Porto Rico (including Santa Cruz) ; Les- 

 ser Antilles: Guadeloupe, Dominica, Martinique, Sta. Lucia. On 

 the continent its range begins in Mexico ; the northern boundary 

 is marked by a line beginning in Tepic Territory, running through 

 the States Jalisco and Guanajuato to Vera Cruz. Thence the range 

 covers the southern parts of Mexico, Guatemala, Nicaragua, Costa 

 Rica and Colombia, and extends eastward over Venezuela (includ- 

 ing Trinidad) and Guyana. In a southerly direction it passes from 

 Colombia into Ecuador, Peru and to Northern Bolivia. In the lat- 

 ter region it is found in the Cordilleras and the tributaries of the 

 upper Amazonas river. An isolated locality is Para, on the southern 

 side of the mouth of the Amazonas river {Pseudothelphusa agassizi 



Rthb.). 



In order to get an idea of the distribution of the different genera 



