IS2 



ISAO IJ1MA. 



but either in the middle of its length or nearer to its one end than to the 

 other, according to whether two opposite principals or a single principal 

 have undergone elongation. The four, equally short, lateral principals, 

 arising from the center at right angles to the shaft as well as to one another, 

 are in most cases all uniterminal, each of them with its single terminal 

 presenting the appearance of a simple ray. It is only very seldom that one 

 or more, though probably never all, of the lateral principals are found each 

 with two or three terminals in a radiating group. Sometimes one meets 

 with cases in which the shaft shows terminals at its each end but is 

 apparently without the cruciate lateral rays. However, it will not take 

 long before the observer is convinced of the fact that he has before him a 

 ■case of hemihexaster, in which only a single principal is prolonged while 

 all the others remain extremely short, and in which the four lateral rays 

 really exist but appear, owing to the proximity of the spicular center to 

 one extremity of the shaft, to constitute a single radiating group of rays in 

 association with the terminals properly belonging to that shaft end. 



In conclusion, it may be stated that A. beatrix oricntalis, subject as it 

 is to very considerable individual variations both as regards its general 

 habitus and the spiculation, on the whole exhibits differentiations in, or 

 tendencies to differentiate toward, the following characters: i) A somewhat 

 diminutive development of macroscopic body parts, in that the body tubes 

 measure generally only 4-S mm. and seldom 10 mm. in diameter, the body 

 wall under I mm. in thickness, and the radial canals of skeleton 0.6-0.8 mm. 

 in width ; 2) Dictyonal septa between radial canals not evenly complanated, 

 a fact which may be correlated with the small caliber of the canals ; 



3) Spikes on the surfaces of dictyonal septa only occasionally present ; 



4) Dermalia largely pentactine and in part hexactine, the hexactins with 

 distal rays which are commonly more or less abortively pinular or are of 

 such a rudimentary development as makes the hexactins gradually merge 

 into the pentactins ; 5) Leptoscopules with terminal swelling of their 

 branches always small, bulb-like and beset with whorls of minute barbs ; 

 and 6) Elongate forms of hemihexasters not over 100/z in length. 



