i54 THE DARWINIAN THEORY 



Developmental evidence we have found to be of 

 the utmost value, for the early stages in the deve- 

 lopment of animals are themselves the very links we 

 want ; sometimes distorted or modified, but usually 

 recognisable with sufficient care. Take, for ex- 

 ample, the fact of the prawn and the barnacle both 

 commencing life in the same form — i.e., the Nauplius. 

 This is evidence of a most cogent character in 

 support of their descent from a common ancestor, 

 and here the Nauplius is the ancestral form, or link 

 from which both were derived. 



Rudiments or vestiges also give most valuable 

 evidence. For instance, the short tail of the crab ; 

 the splint bones of the horse's leg ; the mute letters 

 in our words : points which were fully considered in 

 a previous lecture.* 



Links between the Present and the Past. 



This was Cuvier's difficulty, and formed the basis 

 of an objection which was raised with fatal force. 

 If existing animals are descended from extinct forms 

 or fossils, why do the gaps appear so marked, and 

 where are the intermediate stages which should 

 exist ? 



This question we have already dealt with at length 

 in a former lecture, + where we saw that the objection 

 could be met in its chief part by the imperfection 

 of the geological record. We saw the extreme improb- 

 ability that a continuous series of transitional forms 

 could be preserved, owing to the fact that only cer- 



* See page 95. f See page 60. 



