1002.] AND ANCIENT GEOGRAPHY. 299 



delle Molucche e dell' Australia" [Ann. Mus. Geneva, Sen 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 " {Jbid., Vol. 16, No. 415, 1901), 

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



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



Mus. Paris, 1897, 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 Conwi. 



for 1900, Vol. 2, I901, p. 23). 

 « Description des nouvelles especes de Parathelphusa 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 Fotamonidce Ortm. 

 (= Thelphusidte Dan.) is divided into four subfamilies : PotamonincB 

 Ortm., DeckenimcB Ortm., PotmriocarcinincB Ortm.,^ and Tricho- 

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

 two inhabit the New World.* 



I. Subfamily : Potamonin^. 



The subfamily Potamonince. 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: Parathelphusa M.-E. and Potamon Sav. 

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



^ = Pseudothelphusina 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 Gecarcinuc7is (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. 



PROG. AMER. PHILOS. SOC. XLI. 171. T. PRINTED NOV. 21, 1902. 



