46 



ME. P. H. CAEPENTEE ON THE GENES ACTINOMETEA. 



Table II. — Showing Irregularities in the Position of the first Syzygium. 



In nearly every case the irregularity appears to have been the result of regeneration, 

 the arm having been broken, either in the distichal or in the palmar series, or between 

 the third brachial and the preceding axillary, and a new one developed with an irregular 

 syzygial series ; although in many cases similarly regenerated arms of other specimens 

 exhibit perfectly normal series of syzygia. One of these unusual cases, in which there is 

 no syzygium on the third brachial (b 3 ) and the first syzygium occurs on the tenth seg- 

 ment (6 10 ), which is usually the position of the second syzygium, is seen in PI. II. fig. 8. 



We have seen that when the first syzygium is on the third brachial, the position of the 

 second is in the great majority of cases on the tenth brachial ; that is to say, the first 

 syzygial interval is six simple segments, while the second and all the subsequent intervals 

 are, as a general rule, only three simple segments, though the range of variation on cither 

 side of this number is very great. 



Table III. shows the variations in the positions of the second and third syzygia in all 

 those 283 arms in which the first syzygium is on the third brachial. From the last 

 column of this Table it is evident that in Act. polymorplia and its varieties the normal 

 position of the second syzygium is on the tenth brachial, and that in those cases in 

 which it does not occupy this position it is much oftener on the eleventh or twelfth 

 segment than on the eighth and ninth ; i. e. that variation, when it occurs, is in the direc- 

 tion of increase rather than of decrease in the length of the first interval. This is more 

 clearly seen in Table IV., which shows the number of segments intervening between the 

 first and second syzygia in all the above cases. 



