The Origin of the Markings of Caterpillars. 275 



of the ammonites. In this case also the new 

 characters predominate in the later periods of life, 

 and are then transferred back to the younger on- 

 togenetic stages in the course of phyletic develop- 

 ment. " The change in the character of the shell 

 in ammonites, first makes itself conspicuous in the 

 last chamber ; but in the succeeding generations 

 this change continually recedes towards the be- 

 ginning of the spiral chambers, until it prevails 

 throughout the greater part of the convolutions." 



In the same sense must also be conceived the 

 case which Neumayr and Paul have recently made 

 known respecting certain forms of Melanopsis 

 from the West Sclavonian Paludina bed. In M. 

 Recurrens the last convolutions of the shell are 

 smooth, this being a new character; the small 

 upper convolutions, however, are delicately ribbed, 

 as is also the case with the last convolution of 

 the immediate progenitor. The embryonic con- 



of late years, is foreshadowed by Darwin. Thus, he states 

 when speaking of inheritance at corresponding periods of life : 

 " I could give a good many cases of variations (taking the 

 word in the largest sense) which have supervened at an earlier 

 age in the child than in the parent " (" Origin of Species," 

 ist ed., 1860, p. 444). In the case of inherited diseases also : 

 " It is impossible to ... doubt that there is a strong tendency 

 to inheritance in disease at corresponding periods of life. 

 When the rule fails, the disease is apt to come on earlier in 

 the child than in the parent ; the exceptions in the other 

 direction being very much rarer." ("Variation of Animals 

 and Plants under Domestication," ist ed., 1868, vol. ii., p. 83.) 

 R.M.] 



T 2 



