238 T. IJIMA : HEXACTINELLIDA. 1. 



from the central point of the axial cross and about o'/j ," broad 

 on an average. The slightly swollen end of the principals bears 

 o-o, rarely only 2 or more than o, terminals in a diverging 

 tuft. In the case of oxyhexasters, the number of terminals to 

 each principal frequently runs up to 8, 10 or even more. The 

 terminals are nearly thrice as long as the principal ; they are 

 smooth, tapering, generally not straight but bent in a somewhat 

 wavy manner. When numerous termiuals form a tuft, tliey do 

 not arise in a regular circle, but one or more may occupy a 

 more central position than the rest. The tuft may be so diver- 

 gent that any two opposite standing, outermost terminals 

 form an anole greater tlian 9(j°. F. E. Schulzio has called 

 attention to the fact that in tlie oxystauraster in the type of his 

 Ji. decora, those terminals lying in the plane vertical to that 

 of the four principals stood out from the axis much more 

 divergently than any other terminal. Something like this has 

 also been noticed by me in certaiu instances, but not with 

 any such degree of constancy as justifies one in deducing a rule 

 therefrom. 



The oxystauraster is undoubtedly derived from the oxyhex- 

 aster by the suppression of one of the axes. I have once seen 

 a form with live principals and as many tufts of terminals. At 

 the time I thought it was a genuine oxypentaster, but when I 

 afterwards wanted to confirm my impression that the absence of 

 the sixth arm was not due to a mechanical breaking off, I 

 unfortunately failed to rediscover the rosette. In the few cases 

 of oxystaurasters, in which I have specially entered into the 

 examination of the axial filaments, I have seen no trace what- 

 ever of a third axial filament. 



