dd. Alternation of color on rear of femur not con- 

 spicuous; ist finger generally equal to 2nd; 

 intertympanic space wider (4.5-5.2 in L.); 

 foot with tarsus greater (1. 28-1. 53 in L.). 



Bullfrog. Rana catesbeiana. Plate LXV. 



bb. Rear of femur without alternation of light and dark 

 horizontal bands; edge of jaw mottled, barred, or uni- 

 form. 

 c. Dorsolateral fold absent; size large 3 1/4-5 T /4 

 inches (82-131 mm.); rear of femur, light or white 

 spots on brown; edge of upper jaw mottled; head 

 to angle of mouth 2-2.7 m L.; ist finger 6.5-7.3 

 in L. 



River-swamp frog. Rana hecks chert. Plate LXVIII. 



cc. Dorsolateral fold present, indistinct or absent; 

 edge of upper jaw uniform or barred; size medium 

 to small; first finger 5.-6.8 in L.; head to angle of 

 mouth 2.7-3.4 in L. 

 d. Dorsal folds lacking or interrupted; back and 

 sides mottled or with prominent spots; rear of 

 femur vermiculated in its spotting; males 

 with lateral external vocal sacs somewhat de- 

 veloped; size small 1 7/8-3 inches (48-76 

 mm.); third toe 2.5-2.9 in L.; interorbital 

 space 19-28 in L. 



Mink frog. Rana septentrionalis. Plate LXXV. 



dd. Dorsal fold on cephalic half only; cheek green 

 with mottled jaw below; back uniform or 

 with fine black speckings; rear of femur with 

 fine and scant specklings; males with no 

 lateral external vocal sacs; size medium 2-4 

 inches (52-100 mm.); third toe 2.7-3.7 i n L.; 

 interorbital space 11-23 in L. 



Green frog. Rana clamitans. Plate LXVL 



a. Tympanum of male not enlarged (enlarged in R. onca, rarely 

 in R. areolata and R. sphenocephala) smaller than eye (9-19 

 in L.); throat not so differently colored in males; upper 

 jaw with light stripe or mottling of light and dark; a vitta 

 or regular spots between dorsolateral folds or with yellow, 

 orange or red on hind legs, groin or belly; tibia 1.4-2.3 in L. 

 b. Dorsolateral folds absent or indistinct, low, broken; 

 under surface of hind legs yellow; skin rough; no vitta. 



31 



