STAUnOCALYPÏUS KŒPERI. 171 



fig. 6) and wliieli should occur isolated arc nothing else than 

 such. Their rays are said to be wavy and to have a rough 

 surface (F. E. Sch., '97). 



It frequently happens that in biterminal rays of the oxy- 

 hexasters a third terminal is represented by a minute spine which 

 seems not to have attracted F. E. Schulze's attention. In PL 

 XIV., fig. 28, I have figured a case in which every principal 

 bears a spurious terminal besides two well developed ones. Special 

 examinations were made to convince myself of the fact that the 

 minute spine was not an axial elongation of the principal to 

 which it belonged. In one instance I observed a principal bear- 

 ing two terminals which were quite normally disposed except that 

 one of them was very much shorter and more rudimentary-looking 

 than the other. There can be no doubt whatever that the cases 

 in question represent stages preliminary to the reduction of the 

 number of the terminals. 



The dm-ocladers (PI. XIV., fig. 26) measure 128-180/^ in 

 diameter. Those situated subdermally seem to show no appreciable 

 difierence in any respect from others lying near the gastral surface. 

 The slender secondary principal, not over 4 ,« broad, is nearly as 

 long, in some cases only about h as long, as the free terminals belong- 

 ing to it. The terminals number 2-5, usually 3 or 4, in a tuft 

 which broadens Ijut slightly in the distal direction. They are 

 nearly straight ; the surface is obsoletely rough when seen under 

 a very high power of the microsco])e. The minute terminal disc 

 is always shaped like a pinhcad, and not marginally toothed. 



The delicate microdiscohexasters (PL XIV., fig. 29) are found 

 in tolerable abundance in the gastral region. IJiameter, 22-24 fj. 



