RANINAE 257 



fjeld, at an elevation of 4000 feet, well-nigh the snow-line. In 

 conformity herewith it ascends the Italian Alps up to 10,000 feet. 

 The southern limit in Europe is the Cantabrian range and the 

 hilly province of Galicia. In the rest of the peninsula, in Italy 

 and Lombardy, Greece and Turkey, and on the Mediterranean 

 islands it is absent. 



R. arvalis is often confounded with R. temporaries, as it differs 

 from the latter only by the following characters. The snout is 

 rather more pointed and is narrower ; the inner metatarsal tubercle 

 is large, compressed, and hard ; the dorso-lateral glandular folds 

 are more prominent and the belly is white and immaculate ; lastly, 

 it scarcely reaches 3 inches in length, a size which is not rarely 

 surpassed by the other species. There are also some differences 

 in habits. R. arvalis prefers moist, boggy, open localities, and 

 does not ascend beyond 2000 feet in Central Europe. It pairs 

 as a rule later in the spring and the eggs are smaller, only 1^-2 

 mm. in diameter ; they do not swell up so much, and the whole 

 mass does not float but remains at the bottom of the shallow 

 water. The coloration much resembles that of R. temporaria, 

 and is likewise subject to much variation, except that the pale 

 vertebral stripe is perhaps more common. This species is distri- 

 buted over the whole of Central Europe, Russia, and Western 

 Siberia, south of the 60th degree of latitude, living side by side 

 with R. temporaria. Between the rivers Elbe and Ehine it 

 becomes decidedly rare, and the latter river is practically its 

 western boundary, while the Bavarian Alps and the Danube 

 form its southern limits. 



R. agilis is still more frequently confounded with both the 

 two former species. It differs from either by the absence of 

 the two internal vocal , sacs of the male, and by the decidedly 

 longer hind-limbs, the tibio-tarsal joint reaching often a little 

 beyond the tip of the snout. The inner metatarsal tubercle is 

 as prominent as in R. arvalis. Total length up to 3 inches. 

 The prevailing colour of the upper parts is rather yellow or pink- 

 brown with few and small blackish spots ; a A - shaped dark 

 mark on the neck is often present, and the large dark patch on 

 the temporal regions is always conspicuous. The under parts are 

 white, inclining to lemon yellow on the flanks and thighs. The 

 iris is golden yellow in its upper half, dark brown in the lower 

 half. 



VOL. VIII S 



