22 



THE APODOUS HOLOTHURIANS 



Finally, in conclusion of this section, it may be stated that no subspecies 

 or varieties are accepted. In some cases proposed subspecies, when well char- 

 acterized, have been raised to full specific rank, while more commonly no 

 attempt is made to distinguish them at all. The wide-ranging species are so 

 variable and our knowledge is at present so incomplete, genuine subspecies 

 cannot be positively determined. Until our collections are far more extensive 

 and have been studied with great care, we cannot profitably make use of sub- 

 specific or varietal names. 



