CHORDATA. 9 



cavity is at the hind end ; in the Phoronidea there are indications 

 that the Enteropneust arrangement or a modification of it exists, 

 but the indications are not very clear ; while in the Brachiopoda 

 according to our present knowledge no resemblance to the 

 Enteropneust plan exists save in the enterocoelic origin of the 

 coelom. 



The formation of the coelom in the other chordate phyla, 

 the Annelida, the Mollusca, and the Arthropoda, must be regarded 

 as a modification of the enterocoelic method, but it is never 

 possible in them to trace the arrangement into an unpaired 

 chamber and two pairs of chambers which is so characteristic 

 of the Chordata. 



