FRESH-WATER MALACOSTRACA OF ONTARIO 157 



SESSIONAL PAPER No. 39b 



Di Areola nearly or quite obliterated C. fodiens and diogenes. 



D2 Areola broad. 



El Rostrum nearly square C. hartonii bartonii. 



Eg Rostrum oblong C. bartonii robustus. 



r 

 a . b c d e 



Fig. 10. 



Key based upon the characters of the large chelipeds. (Fig. 10). 



Ai Carpus without ventral median anterior tooth. Inner border of hand or pro- 



podus straight C. propinquus. 



A2 Carpus with ventral median anterior tooth. Inner border of propodus curved. 

 Bj Two teeth on ventral margin of joint between dactyl and propodus. C. virilis. 



B2 No teeth on ventral margin of that joint C. bartonii. 



B3 One distal tooth on ventral margin of that joint. Dactyl not excavated at 



base C. limosus. 



B4 One median tooth on ventral margin of that joint. Dactyl excavated on 

 outer side near base C. fodiens. 



Cambarus bartonii (Fabr.) Figs. 8, e; 9, e, f; 10, d; 12, c. 



Hagen, p. 75; Faxon, p. 59; Ortmann, p. 120. 



This is perhaps our commonest crayfish. It is found under stones, etc. in 

 running or open water, often at considerable depths. According to Abbott (see 

 Faxon) it sometimes burrows in muddy banks. It has been reported from St. 

 John, N.B., to Lake Superior on the north. 



Localities. — Lake Superior (Hagen). Searchmont (Algoma District), 

 (Williamson). 



Georgian Bay: Giant's Tomb, Go Home, Shawanaga, Bustard Ids., French 

 River (Wo) ; Go Home from fish nets (Wa) ; Copperhead Id. 



Grant River (Brant Co.), Welland River. 



Niagara (Hagen). 



Humber and Don Rivers near Toronto (Hagen). 



Iroquois (C). 



Length up to 100 mm. Antennae frequently longer than body. Rostrum 

 without lateral teeth, in shape from nearly square to rather long rectangular. Areola 

 from 1/7 to 1/10 the width of the carapace. Only one distinct spine on each side 



