132 THE APODID^E PART i 



Having so far considered the typical Crustacean 

 glands, the antennal, shell, and leg glands, and 

 homologised them with setiparous glands of the 

 original Annelid, it is necessary, in order to establish 

 the close relationship which we maintain exists 

 between Apus and the Annelida, to discuss the 

 typical excretory organs of the latter (*>., the 

 nephridia), and to endeavour to discover their fate 

 during the transformation of the Annelid into the 



o 



Crustacean. 



Professor Haeckel, in the last edition of his Natural 

 History of Creation^ characterises the Crustacea as 

 segmented animals without nephridia, and the worms 

 as segmented animals with sea-mental organs or 



o o <_> 



nephridia, the presence or absence of these latter 

 being the chief characteristic difference. The stress 

 here laid by so distinguished a zoologist upon the 

 nephridia as a class characteristic renders it doubly 

 necessary cither to find the nephridia in Apus our 

 primitive Crustacean or to give some probable 

 explanation of their absence. Although no expla- 

 nation of the absence of nephridia \vas immediately 

 evident, we were convinced that it would some day 

 be found. We would not allow that the difficulty 

 of finding a set of organs in Apus to homologisc 

 with another set in the Annelida though no doubt 

 serious could destroy the value of the mass of 

 evidence already obtained as to the relation of 

 Apus to the Annelids. This reasoning is further 

 especially applicable in the case of the Annelidan 



1 Ed. viii. 1891, p. 570. 



