THE BATRACHIA OF NORTH AMERICA. 397 



the vomerine teeth iu Rana temporaria pretiosa are not appreciably 

 more posterior in position than in Rana septentrionalis, in which case 

 the species approach each other very closely. The Bana septentrionalis 

 violates the characters which distingaish the R. clamata and R. cates 

 hiana from each other, and would afford a complete connection between 

 them were it not fur its inferior size; but even this point does not in. 

 variably hold good, as a few specimens of R. clamata do not exceed it 

 in dimensions. Three specimens have been found which relate very 

 closely the R. silvatica and R. cantahrigensis, two of which are referred 

 to the former and one to the latter species on olher characters, which 

 are not numerous. A subspecies latiremis of R. cantahrigensis, from 

 Alaska, approaches the R. temporaria in its wide palmation ; and there 

 is a specimen (9420) which is quite intermediate between the R. agilis 

 and thei2. draytoni. The chain of affinities indicated by these interme- 

 diate specimens may be sketched as follows : 



•Soptentrionalis 



Silvatica' 



Temppr 

 CantabrigeDsis. 



These series are not probably genetic, as some of the species have 

 been most likely derived from the Old World, The R. septentrionalis, 

 however, may be very probably ancestral to the forms of the Cates- 

 biana series, and perhaps of others. 



The species of Eana are well protected from enemies by an extremely 

 acrid secretion of the skin. An animal of much superficial sensitive- 

 ness is not likel}^ to take a frog into the mouth a second time. Do- 

 mesticated dogs and cats avoid them, but snakes evidently have no such 

 scruples against feeding on them. 



RANA VIRESCENS Kalm.* 



Resa til Nona America, iii, 1861, p. 46 ; Schreber, cler Naturforscher, xviii, 

 1782, p. 185; Pi. iv. Ganuan, Ball. Esses Iast.,xvi, p. 41. 



Eena halecina " Kalm," Schreber, /. c, nee. Icalmii ; Daudin (Kalm), Hist. Nat., Reptil., 

 vm (1803), 122, 432; lb. Hist. Nat. Rain., etc. (1803\ 63 ; Harlau, Sillim. Amer. 

 Jour. Sci., X (1825), b. 1. ; Journ. Ac. Nat.Sci. Phila., v (1827), 337; 1 b. Med. 

 aud Phys. Rept.(1835), 102-224 ; Storer. Rept. Mass. Reptil. (18.39), 237 ; Holb., N. 

 Amer. Herp., 1st ed., i (1836), 89, xiii; 1 b.2d ed,iv (ld42), 91, xci ; Dnm. & 

 Bibr.,Erp.G6u.,viii (1841), 352; Tliompsou, Nat. Hist. Vt. (1842), 120; De Kay, 

 N.Y.ZooI., 111(1842), XX, fig. 49; Hallow., Proceed. Ac. Phila. (1856), 141. 



Bana aqiiaUca (water frog), Catesby, Carol., ii (1743), 70; Klein, Quadruped, p. 119. 



Sana pipiem Gm., cd. L, Syst. Nat. (178S), 1052, 28; Bonnaterre, Eucyclop. Meth. 

 Erpet. '',1789), 5, ix, fig. 2 ; Schueider, Hist. Amph. fasc. 1 (1799), 153; Shaw, Gen. 

 Zool., Ill, Amph. (1802), 105. 



Eana utricularia Harlan, Sillim. Journ., x (1825), 60; Journ. Ac. Nat. Sc.,v (1827), 

 337 ; 1 b. Med. and Phys. Rept. (1835), 102, 223. 



* Plates 50, figs. 1, 2; 51, figs. 1, 9. 



