. Echinoidea. Sea urchins. ECHINOIDEA. II. 171 larger specimen (130'""^) I count 7—8 such piates in each series, all being provided with a pore. Of tlie iiiiier plate without pore 110 trace is seen, and since there is otherwise such a plate for each three pore-bearing piates, this faet must mean that the poreless plate becomes absorbed on passing to tlie buccal membrane. On the abactinal side it is seen that the larger primary plate is from the beginniug undivided; but already from the third or fourth the dividing line has appeared, though not easily discernible before nearer to the
. Echinoidea. Sea urchins. ECHINOIDEA. II. 171 larger specimen (130'""^) I count 7—8 such piates in each series, all being provided with a pore. Of tlie iiiiier plate without pore 110 trace is seen, and since there is otherwise such a plate for each three pore-bearing piates, this faet must mean that the poreless plate becomes absorbed on passing to tlie buccal membrane. On the abactinal side it is seen that the larger primary plate is from the beginniug undivided; but already from the third or fourth the dividing line has appeared, though not easily discernible before nearer to the ambitus. All the pores are distinct, only that of the inner small plate distinctly the larger, corresponding to the larger size of the tubefoot of this Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Mortensen, Th. (Theodor), 1868-1952. Copenhagen, Printed by Bianco Luno
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Keywords: ., bookcentury1900, bookcollectionbiod, bookdecade1900, bookyear1903
