204 AMPHIBIA 



cal eggs, twenty or more in number, measure four or five milli- 

 metres in diameter; they are unpigmented and were first 

 believed to be of the meroblastic type. A more careful investi- 

 gation has, however, shown that the cleavage extends through 

 the whole ovum. The segmentation is holoblastic, but of that 

 same intermediate type which has been observed in Alytes, 

 Rhacophorus, and other forms in which the growing embiyo oc- 

 cupies a position on the yolk strikingly like that of a fish embryo. 

 The total cleavage is slow in appearing, and in the later stages 

 of development the yolk-mass becomes homogenous by the dis- 

 appearance of cell-walls. The larvae, breathing though external 

 gills, remains in the egg-capsule until about twenty to thirty milli- 

 metres in length, the rest of the development being undergone 

 in the water. Except for the fact that the female instead of 

 the male takes charge of the progeny, the development of Des- 

 mognatkus is a very close parallel to that of Alytes. 



(2) D. The genus Salamandra is represented in Europe by 

 two very closely allied species, of terrestrial habits, which are 

 both viviparous ; but whereas in one the young are born as a 

 rule in the branchiate, larval condition, the other gives birth 

 to perfect salamanders, differing only in size from the 

 parents, and fitted for terrestrial life. 



The first species, the yellow-spotted or fire salamander, 

 5. maculosa, lives in the plains or at low altitudes in the 

 mountains (up to 2800 feet). It pairs on land, and several 

 months later the female goes to the water and gives birth to 

 ten to fifty young, of small size and similar to newt larvae 

 with the four limbs developed. 



The second species, the black salamander, S. atra, is of 

 smaller size and inhabits the Alps between 2000 and 9000 feet 

 altitude. Localities at such elevations are not, as a rule, 

 suitable for larval life in the water, and the young are there- 

 fore retained in the uterus until the completion of the meta- 

 morphosis. Only two young, rarely three or four, are born, 

 and these may measure as much as fifty millimetres at birth, 

 the mother measuring only 120. The mode of reproduction 

 of this salamander is very remarkable indeed, and unique of 

 its kind. The uterine eggs are large and numerous, but as a 

 rule only one fully develops in each uterus, the embryo being 

 nourished on the yolk of the other eggs. The embryo passes 



