1902.] AND ANCIENT GEOGRAPHY. 295 



be over India and China, generally over Southern and Eastern 

 Asia. Under this assumption, that crayfishes formerly existed in 

 Southeastern Asia, it also becomes clear by which way the rest of 

 the Parastacidce were geographically connected with the Potamo- 

 biidce, namely, by way of the Indian Archipelago, from the conti- 

 nent of Asia over the Sunda Islands, New Guinea to Australia. 



Looking over the various connections between the different 

 isolated areas of distribution of the different groups of crayfishes, 

 which have been suggested by the above chorological and system- 

 atical discussions, we may itemize them in the following way : 



i. A connection of East Asia with North America by way of 

 Bering Sea. 



2. A connection of Cuba with Central America (Mexico). 



3. A connection of New Zealand with Australia, possibly over the 

 Fiji Islands and New Guinea. 



4. A connection of Australia or New Zealand with South Amer- 

 ica. 



5. A connection of Southeastern Asia with Madagascar and with 

 Australia. 



We need further explanation of the following remarkable facts : 



1. The absence of Potamobiidce in Central Asia. 



2. The absence of crayfishes in Southeastern and Eastern Asia. 



3. The remarkable geographic restriction and isolation from each 

 other of the crayfishes of the genera Potamobius and Cambarus in 

 North America. 



4. The remarkable boundaries of the area of Parastacus in South 

 America. 



B. Chorology of the Family ^Egleid^e 1 (See Fig. 2). 



Here we shall leave for the present the crayfishes of the families 

 of the Potamobiidce and Parastacidce. and shall take up the small 

 group formed by the sEgleidce of Dana. This seems to be a mono- 

 typic family, consisting only of one genus and one species, sEglea 

 Icsvis (Latr.). The following localities are recorded for it : 



Chili : Valparaiso, and between Valparaiso and Santiago ; Lake 

 Llanquihue, near Puerto Montt. 2 Argentina : Provinces Jujuy 



1 See Ortmann, 1901, p. 1290. 



2 Doflein, F. SB. Akad. Muenclien, V. 30, 1900, p. 135. 



