VERTEBRATE ZOOLOGY. 473 



differing in those respects; but, nevertheless, among Am- 

 phibians, there are several marked cases of deviation from 

 the rule. One of the most interesting concerns the life-his- 

 tory of two species of Salamanders. These are inhabitants 

 of Europe, one a common and widely distributed species 

 the Salamandra maculosa, and the other an Alpine species 

 the Salamandra atra. Both are viviparous, and in each ovi- 

 duct there are between 40 ami 60 eggs ; but there is, normal- 

 ly, a great difference between the offspring of the two spe- 

 cies when first excluded by the mother. In the Salamandra 

 maculosa, almost all the eggs are fertilized and equally de- 

 veloped, and about 40 or 50 young are born, which retain the 

 embryonic gills, and are very small and soft-skinned. In the 

 Salamandra alpina, however, only the eggs nearest the ovi- 

 duct are fructified, and generally not more than two young 

 become fully developed, and these remain within the body of 

 the mother, feeding on the neighboring embryos or eggs, un- 

 til they attain a length of about two inches. At birth they 

 have lost their gills, are vigorous and well developed, and 

 the skin is provided with the glands which secrete a nause- 

 ous defensive fluid characteristic of the adult. Such are the 

 normal conditions. 



But lately an enthusiastic and talented lady naturalist, 

 Miss von Chauvin, has shown that there is no radical physi- 

 ological difference between the two species, and that the 

 young of the Salamandra alpina will survive, if exposed at 

 the same stage of development that the Spotted Salamander 

 exhibits at birth. That lady took from the uterus 23 larvae 

 provided with gills, and put them in water. Most of them 

 soon died ; but two lived, one of which exhibited all the lar- 

 val characteristics, while the other resembled the mother, but 

 retained the gills. Both these and the ones that died ap- 

 peared to be perfectly "at home" in the water, and swam 

 freely about. In the survivors, however, the long-training 

 embryonic gills became withered, and these seemed then to 

 inconvenience the animals, and were soon thereafter rubbed 

 off. The larvae then rested quiescent in the darkest part of 

 the vessel in which they were confined for several days ; after, 

 " on each side of the head, just in the position of the old gills, 

 three little processes appeared, and soon increased till they 

 took on the form of small bladders, provided with a close 



