NOTES ON ECFlINODEflM MORPHOLOGY. 321 



tube of the cystid phase '' s^ouvre a I'exterieur par un pore 

 situe sur la parol du corps." He does not refer at all to 

 Ludwig's careful description of the independence of the inner 

 ends of the water-tube and water-pore respectively ; and as he 

 gives no figures in illustration of his statement, I am not 

 inclined to believe it, especially as it would be totally incon- 

 sistent with our knowledge of the structure of these organs in 

 the later stages of development, and in the adult Crinoid, as 

 Perrier's own observations show. 



Towards the end of the next or pentacrinoid stage there are 

 five tubes and five pores, one in each interradius ; and Perrier 

 admits that the inner ends of these "tubes hydrophores^' appear 

 in his sections " se terminer par une extremite libre dans la 

 cavite generale, mais nous avons des raisons de penser que ces 

 tubes sont normalement en continuite," with the inner ends of 

 the fine funnel-shaped water-pores. He does not state these 

 reasons, however, but goes on to say that in the latest penta- 

 crinoid condition, just when the young animal is about to 

 detach itself, " les tubes hydrophores se sont considerablement 

 multiplies, mais on observe les memes rapports entre eux et 

 les canaux qui traversent la parol du corps pour s'ouvrir a 

 I'exterieur.^' 



I have not made many observations regarding this point, as 

 I considered it to have been settled by Ludwig ; but from what 

 I have seen I am fully prepared to support his view of the want 

 of connection between the primary water-tube and water-pore; 

 while there is every reason to believe that the condition of the 

 Pentacrinoid is represented permanently by that of Rhizo- 

 crlnus. This type has only one tube and one pore in each 

 interradius, and they are not directly continuous, but com- 

 municate with one another through the intervention of the 

 body-cavity. 



Perrier's last statement respecting the multiple water-tubes 

 of the late Pentacrinoid and young Comatula is a very 

 cautious one. It reads as if he meant to imply that the 



1 I have only found one pore iu larvae with a completely formed chambered 

 organ, while individuals with five cirrus-stumps have Only two. 



