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Northern Crayfish, Orconectes virilis: Measurements and Ratios: Form I Male
Number Minimum Maximum Mean
Total length 357 45.4 116.1 81.7
Carapace
Total length 357 22.6 61.2 41.4
Postorbital length 356 17.3 48.7 32.4
Aureola
Length 357 8.0 23.4 15.1
Width 357 0.1 1.8 0.8
Chela
Total length 354 16.8 70.1 39.3
Dactyl length 354 9.0 49.1 27.5
Palm length 354 4.5 16.8 9.7
Palm width 354 1.3 28.3 15.6
Finger gap 354 0.0 8.9 3.2
Antenna
Total length 344 30.5 115.6 72.3
Pleopod
Total length 357 9.4 24.2 16.7
Central projection 357 2.9 8.1 5.6
Ratios Number Minimum Maximum Mean
Carapace length / Total length 357 0.48 0.57 0.51
Aureola length / Carapace length 357 0.31 0.39 0.37
Aureola length / Aureola width 357 8.3 43.1 19.0
Chela length / Carapace length 353 0.68 1.17 0.94
Dactyl length / Chela length 353 0.52 0.78 0.70
Palm width / Chela length 353 0.29 0.47 0.40
Pleopod length / Carapace length 357 0.34 0.49 0.40
Central Projection length / Pleopod length 357 0.26 0.44 0.34
