256 ANURA CHAP. 



March. On the 15th the larvae were 4 mm. long and began to 

 leave the eggs. On the 19th they measured, body 4, tail 9, total 

 13 mm.; on the 5th of April 10, 16, and 26 mm. respectively. 

 On the 13th of May they were 40 mm. long and the hind-limbs 

 appeared; the fore-legs burst through on the 25th, when the 

 tadpoles had reached their greatest length, namely 45 mm., the 

 body measuring 15 mm. On the 31st of May they left the 

 water, still provided with a rather long tail of 20 mm., the total 

 length being reduced to 3 5 mm. The larvae of this set developed 

 unusually fast, perhaps owing to artificial conditions. The whole 

 development is, however, mostly finished in three months, so that 

 the little stump-tailed baby-frogs swarm about well before mid- 

 summer, and have time enough to grow to the size of 20 mm. or 

 J inch before they begin to hibernate in October. 



In higher localities and in northern countries the tadpoles 

 are sometimes obliged to winter in the unfinished condition. 



In spite of the unusually hot summer of 1899 I found 

 plenty of tadpoles on the 10th of September in the tarns of the 

 hills of North Wales, 1500 feet above the level of the sea ; while 

 thousands of little frogs, with and without stumpy tails, were 

 hopping about in the surrounding bogs. The water of these 

 tarns is always very cool. Cold and rainy weather set in by the 

 middle of the month, and on the 26th the tadpoles, all rather 

 small, measuring only 3 5 mm., with the four limbs developed, but 

 still with a broad fin on the tail, had all settled down under 

 stones at the bottom of the now very cold water, prepared for 

 hibernation. A few were taken home and kept in a glass vessel 

 with water, cool, but less so than that of their native tarns. 

 Within two days they lost the fins on their tails ; before the 

 end of a week they left the water, and crawled on to the moss, 

 and the tails were reduced to little stumps. By the 10th of 

 October the metamorphosis was complete, the little frogs measured 

 only 13 mm. in length and showed no desire to hibernate in the 

 genial atmosphere of the greenhouse. 



This species has a very wide distribution. It ranges from the 

 west of Ireland to the islands of Saghalin and Yezzo, being found 

 everywhere in the enormous stretch of intervening countries, 

 practically the whole of Central and Northern Europe and the 

 middle belt of Asia. Its most northern extent is the whole of 

 Sweden and Norway. I have found it to the east of the Dovre- 



