SECT. I OBJECT AND LINE OF ARGUMENT 7 



the excretory and other glands, and, lastly, the repro- 

 ductive organs. We shall either point out the 

 resemblances in each case between these organs and 

 those of our Annelid, or else show how they can be 

 deduced from Annelidan organs. It will be found 

 that while some of the modifications of Annelidan into 

 Crustacean organs are easy to follow, the explanation 

 of others has to be sought, and may thus appear to be, 

 in some cases, far-fetched. 



And here we must remind our readers that it is 

 enough for our argument if we can show that such a 

 deduction is possible. It is not essential to our theory 

 that we should show exactly Jiozv the inner transform- 

 ations actually took place. Our explanations may 

 themselves be incorrect, but the validity of our argu- 

 ment can only be seriously weakened by showing that 

 a set of organs in Apus could not possibly have been 

 derived from any organs in the Annelida ; or that the 

 improbability of such a transformation is so great that 

 no experienced morphologist would accept it. 



We shall conclude the first part of this essay by an 

 appeal to the Nauplius, to see whether it bears out our 

 theory that Apus is the original form of the majority 

 of the modern Crustacea ; or, in other words, whether 

 Apus can itself claim to be the proto-Nauplius of 

 zoologists. We shall endeavour to describe the exact 

 morphology of the Nauplius considered as the Apus 

 larva or the Apus-stage in the development of the 

 other Crustacea. 



This will conclude Part I., which we hope will have 

 shown that, so far as such claims can be based purely 



