ANIMAL PEDIGREES 235 



larval stages were omitted in all the members of a 

 group, we should have no direct evidence of de- 

 generation in a group that might really be in an 

 extremely degenerate condition. Supposing for 

 instance the free larval stages of the solitary 

 Ascidians were suppressed, say through the acqui- 

 sition of food yolk, then it is urged that the 

 degenerate condition of the group might easily 

 escape detection. The supposition is by no means 

 extravagant. Food yolk varies greatly in amount 

 in allied animals, and cases like Hylodes, or 

 amongst Ascidians, Pyrosoma, show how readily a 

 mere increase in the amount of food yolk in the egg 

 may lead to the omission of important ancestral 

 stages. 



The question then arises whether it is not 

 possible, or even probable, that animals which now 

 show no indication of degeneration in their de- 

 velopment are in reality highly degenerate, and 

 whether it is not legitimate to suppose such de- 

 generation to have occurred in the case of animals 

 whose affinities are obscure or difficult to determine. 

 It is more especially with regard to the lower 

 vertebrates that this argument has been employed ; 

 and at the present day zoologists of authority, 

 relying on it, do not hesitate to speak of such 

 forms as Amphioxus and the Cyclostomes as de- 

 generate animals, as wolves in sheep's clothing, 

 animals whose simplicity is acquired and deceptive 

 rather than real and ancestral. 



I cannot but think that cases such as these 

 should be regarded with some jealousy ; there is 



