176 THE APODID^E PART n 



bent Annelid, will establish our main argument be- 

 yond contradiction. We shall therefore devote our 

 chief attention to endeavouring to explain the mor- 

 phology of these ancient forms from this point of view, 

 making, as we believe, many points clear which have 

 never been properly understood. 



As to the second part of our task, the deduction of 

 the modern Crustacea from the Apodidx, and the 

 formation of a new system of classification, we shall 

 have to leave the working out of the details to others, 

 and content ourselves with a short collection of 

 notes, to suggest the possible ways in which the 

 modern Crustacea may be deduced from our bent 

 Annelid, either through Apus or through the Trilo- 

 bites. 



APUS AND LIMULUS. 



We begin with Limulus because, being still extant, 

 its anatomy is well known. It is to the works of 

 Anton Dohrn, Kingsley, Lankester, Milne-Edwards, 

 Packard, and others, that we are indebted for the 

 details of its organisation here brought forward. 



The likeness between Limulus and Apus is so 

 great, not only in external form but in inner organisa- 

 tion, that almost all the older zoologists classed them 

 together in one genus. The temptation to draw com- 

 parisons between them is traceable in the writings of 

 all who have dealt with either of them. But, in spite 

 of this unmistakable likeness, all idea that the two 

 animals could possibly be related has in later times 

 been steadily repudiated. Indeed no general agree- 



