Echinoidea (1903) Echinoidea echinoidea00mort Year: 1903 6o ECHINOIDEA. II. have constaiith' foxind both the iuiier piates of I and V developed; but the piates I. b. i and V. a. i are generally very small and easily overlooked. The piates I. a. i and V. b. i may be ver\- unequally developed, one of them siniulating the labrnni, but the presence of the pore at its inner end shows its real natnre. Generally onl\' the four larger of these piates bear distinct pores and tnbe-feet, in the otlier piates only qnite rndimentary pores are present, sonietinies the pore has even quite disappeared. Resid
Echinoidea (1903) Echinoidea echinoidea00mort Year: 1903 6o ECHINOIDEA. II. have constaiith' foxind both the iuiier piates of I and V developed; but the piates I. b. i and V. a. i are generally very small and easily overlooked. The piates I. a. i and V. b. i may be ver\- unequally developed, one of them siniulating the labrnni, but the presence of the pore at its inner end shows its real natnre. Generally onl\' the four larger of these piates bear distinct pores and tnbe-feet, in the otlier piates only qnite rndimentary pores are present, sonietinies the pore has even quite disappeared. Resides the snpposed coalescence between the two inner piates of ambulacra I and \', Loven, j^oints out (Op. cit. p. 36) as another pecnliar feature in this species, that the inner piates of ambulacra II and IV are not in accordance with the general rule that the piates La, II. a, III. b, IV. a, V. b are the largest. I have constantly found the inner piates of the paired ambulacra to be in accordance with the rule, only as to ambulacrum IV I have sometimes been unable to see it distinctly. As it seems ver\' unlikely that all the specimens examined by Loven should happen to be abnormal in this respect, I must venture to suggest that Loven has overlooked some of these small piates, which mav, indeed, be rather difficult to see. (I have found them easiest to discern when the denuded test in alcohol; on dried tests, treated with alcohol-glycerine it is almost impossible to trace the limits between the small piates). A very small plate may sometimes be found be- tween the inner piates of the ambulacra I and II on one side and IV and V on the other side (PI. VIII. Figs. 5, 8, 9, 11). It must doubtless be regarded as the rndimentary inner plate of the interambulacra i and 4. Whether this plate was really absent in Lov én's specimens or perhaps was overlooked, it follows from its occasional (not ver}- seldom) occurrence that the piates interpreted by Loven as No. i of the intera
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