THE SYSTEM OF PIIYLLOPHORIN..E. 



6S 



Semper has interambulacra either provided with pedicels in scattered 

 distribution or totally devoid of these. 



On the other hand, there are reasons to think that the number 

 and arrangement of tentacles are something which is more constant 

 than the distribution of pedicels and papilla?. The fact that, except 

 in the Synaptida?, the tentacles attain their full complement of number 

 relatively early in the postembryonal development, is known from 

 several cases of Holothurians, but unfortunately not from any 

 polychirotous form. 



All previous records of Cucumarid species said to possess ten- 

 tacles in a number other than multiples of five, excepting the eight- 

 tentacled Sphœrothuria bitentaculata LUDWIG [29, pp. 148 — 149], are 

 presumably based either on specimens which had accidentally lost 

 some of their tentacles or on otherwise insufficient observations. It 

 seems only fair to assume that except in abnormal individuals there 

 can be no really congenital deviation of tentacle number from a 

 multiple of five. 



The two specimens of Pseudocucumis japonicus which were given 

 by Bell [5, p. 253] to possess twenty-four tentacles, when later 

 re-examined by Bedford [4, p. 845] were found to possess twenty- 

 five and twenty-three tentacles respectively. MlTSUKURl ascribed 

 seventeen tentacles to a specimen of Phyllophorus japonicus [32]. and 

 fifteen to Ph. fragilis (see p. 82), but the specimens, as re-examined 

 by me, were found to have in reality twenty tentacles each. While 

 Lam pert [18, p. 255] has described his Pseudocucumis intercedens to 

 possess only eighteen tentacles, LUDWIG [23- P, 26] identified with it 

 thirty-tentacled specimens. 



Among the numerous specimens of Pseudocucumis examined by 

 me, some were found to have a tentacle more and others with a few 

 less than the normal number. The cases seem to deserve to be 

 noticed here in short. One individual of Pseudocucumis africanus 

 was provided with twenty-one tentacles, and another of Ps. japonicus 



