AMERICAN FROGS OF THE GENUS RANA. 



457 



Measurements in millimeters. 



1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 



From snout to vent 40 40 44 44 43 56 50 37 37 46 43 51 



Head 14 14 15 15 14 17 16 13 13 16 14 16 



Width of head 15 14 16 15 15 19 17 14 13 17 15 17 



Snout 4.5 4.5 5 5 5.5 6 5.54.54.5 656 



Eye 4.5 4.5 5 5 5 6 5.54.54.5 656 



Interorbital width 2.5 2.5 3 2.5 3 3 2.5 2 2 2.52.52.5 



Tympanum 3 3 2.5 3 2.5 3 3 2 2 3 2 3 



ForeUmb 22 20 25 25 24 30 28 20 21 26 25 27 



1st finger 4 4 4 4 4 7 5 3.5 4 4.54.5 5 



2nd " 3.53.53.53.53.55.5 4 3 33.53.5 4 



3rd " 6 6 6.5 6 6 8 6.5 5 5 6.56.5 7 



4th " 3 3 3 3 3 5 3.52.52.5 3 3 3 



HindUmb 58 60 67 67 66 83 76 52 55 75 72 70 



Tibia 17 18 20 20 19 25 22 15 16 23 21 20 



Foot 19 20 23 23 22 27 24 17 18 25 25 23 



3rd toe 10 11 13 13 12 14 13 9 10 13 12 11 



4th " 15 15 18 18 17 22 20 14 15 20 20 18 



5th " 10 10 11 11 11 13 12 9 10 13 12 11 



1-2. Port Smith, Great Slave R., Canada. — 3-5. Banff, Alberta. — 6-7. Rocky 

 Mts., B. N. A.— 8-9. Great Bear Lake.— 10-11. Stanley, Wise— 12. N. 

 America. 



The larva is unknown. 



Habitat. — Western North America, from Alaska and Great Bear 

 Lake to British Columbia, Alberta, Assiniboia, Manitoba, Minnesota, 

 and Illinois. 



As pointed out by Howe it is almost certain that the type specimen 

 was not preserved in Massachusetts by Agassiz, but was sent to Baird 

 from Cambridge, whence the confusion. 



R. cantabrigensis is the American representative of R. arvalis, 

 from which it differs in but very trivial characters. Had I not 

 attached importance to the absence of the A-shaped interscapular 

 marking in all the American frogs, I might have been tempted to 

 degrade R. cantabrigensis to the rank of a variety of R. arvalis, as I am 

 much struck by the resemblance in the cranial characters. It is also 

 noteworthy that the light vertebral line is found in no other North 

 American species, and the light line along the liind limb is a character 

 met with, irrespective of affinities, in many forms from the African 



