. Echinoidea of the Swedish South Polar Expedition . Figs. 10 â11. Transverse sections of spines of. Arbacia crassispina (10) and A. Dufresnii (11). In the above quoted work of AGASSIZ & CLARK: .Hawaiian and other Pacific Echini. The Salenida;, Arbaciadas ....â » it is stated (p. 109, Note) that in my dis- cussion of the systematic value of the character afforded by the ambulacral structure of the regular Echinoids (Siam-Echinoidea I. p. 42), the result being that the three main types of ambulacral structure, viz. the cidaroid, the diadematoid and the echi- noid type, must be regarded as
. Echinoidea of the Swedish South Polar Expedition . Figs. 10 â11. Transverse sections of spines of. Arbacia crassispina (10) and A. Dufresnii (11). In the above quoted work of AGASSIZ & CLARK: .Hawaiian and other Pacific Echini. The Salenida;, Arbaciadas ....â » it is stated (p. 109, Note) that in my dis- cussion of the systematic value of the character afforded by the ambulacral structure of the regular Echinoids (Siam-Echinoidea I. p. 42), the result being that the three main types of ambulacral structure, viz. the cidaroid, the diadematoid and the echi- noid type, must be regarded as characters of orders, I have made a curious slip, having overlooked that DUNCAN & SLADEN have shown the ambulacra of Tetra- pygus to be of the echinoid structure, not of the diadematoid, as are those of the other Arbaciids. They conclude the note with the remark: »Are we to presume that Dr. Mortensen will establish a family »Tetrapygidae» under his »Tribus 4. Echinina* for this aberrant genus?» It is true that I have overlooked DUNCAN & SLADEN's statement * about the ambulacra of Tetrapygus, and I have no excuse for that. But I might suggest * On the Family Arbaciadoe Gray. Part I. The Morphology of the Test in the Genera Coleopleurus and Arbacia. Journ. Linn. Soc. Zoology. Vol. XIX p. 53. PI. II. 6. I
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Keywords: ., bookcentury1900, bookcollectionbiod, bookdecade1910, bookyear1910
