1902.] AND ANCIENT GEOGRAPHY. 299 



delle Molucche e dell' Australia" [Ann. Mus. Génova, Ser. 2, Vol. 20, 



1899, pp. 261-264). 



Nobili, G. : " Decapodi e Stomatopodi Indo-Malesi " [Ibid., Ser. 3, Vol. 20, 



1900, pp. 499-504). 



" Decapodi raccolti dal Dr. Filippo Silvestri nell' America meridionale " 



{Boll. Mus. Torino, Vol. 16, No. 402, 1901). 

 " Viaggio del Dott. Enrico Festa nella Republica dell' Ecuador. 



Decapodi e Stomatopodi " {Ibid., Vol. 16, No. 415, 1901). 

 Rathbun, M. J. : " Descriptions de nouvelles espèces de Crabes d'eau douce 



appartenant aux collections du Museum d'histoire naturelle de Paris " {Bull. 



Mus. Paris, 1 897, pp. 58-61). 

 " Descriptions of Three New Species of Freshwater Crabs of the Genus 



Potamon " {Pr. Biol. Soc. Washington, Vol. 12, 1898, pp. 27-30). 

 "The Decapod Crustaceans of West Africa" {Pr. U. S. Mus., Vol. 22, 



1900, pp. 282-285). 

 " The Brachyura and Macrura of Porto Rico " {Bull. U. S. Fish Comm. 



for 1900, Vol. 2, 1901, p. 23). 

 " Description des nouvelles espèces de Pavathelphusa appartenant au 



Museum de Paris " {Bull. Mus. Paris, 1902, p. 184 ff.). 

 Weber, M. : «'Die Decapoden Crustaceen des Suesswassers von Sued-Afrika " 



{Zool. Jahrb. Syst., Vol. 10, 1897, p. 156). 



According to Ortmann (1897) the family of Potamonidce Ortm. 

 (= Thelphusidce Dan.) is divided into four subfamilies : Potamoninoz 

 Ortm., Deckeniince Ortm., Potamocarcinina Ortm., 1 and Tricho- 

 dactylinoz Ortm. The first two belong to the Old World, the last 

 two inhabit the New World. 2 



1. Subfamily: Potamonin^e. 



The subfamily Potamoninoz is in very poor condition, systemati- 

 cally. Not only our knowledge of the very numerous species is 

 rather incomplete, but also their arrangement into genera and sub- 

 genera is by no means satisfactory. Generally, it seems that we can 

 distinguish two genera: Paraihelphusa M.-E. and Potamon Sav. 

 (= Thelphusa Latr.J, to which possibly a third one is to be added, 



1 = Pseudothelphusince Ortmann and Rathbun (1898, p. 508). The division 

 into genera varies considerably with Ortmann and Rathbun respectively (see 

 below) , and the name of the subfamily depends on the classification accepted. 



2 According to Alcock {Journ. Asiat. Soc. Bengal, Vol. 69, 1900, p. 279), 

 also Gecarcinucus (one species in the peninsula of India), which was placed 

 hitherto with the family Gecarcinidce, belongs to the Thelphusidce (= Pota- 

 monidce'). If this is so, we ought to create, possibly, a separate subfamily for 

 this genus. 



