122  @ Wachsmuth—Structure of Paleozoic Orinoids. 
out, their ventral furrows are open, the quadrangular pieces in 
place, their tooth-like extensions stand out like the teeth of a 
saw, and are so arranged that the indentations face the salient 
angles of the opposite side, thus giving to the furrow a strongly 
the neo themselves, and especially by the manner of their 
chment. The inner edges of the quadrangular plates (be- 
small movable plates are evidently homologous with the 
‘“ saumplatten” of Antedon, and the imbrications of these 
plates, as well as of the entire covering, seems to hint at the 
conclusion, that the furrow was always closed when the arms 
were folded up as in Mr. Springer’s specimen; but that on the 
contrary, as in my specimen, the furrow was open when the 
peur spread, and that in this position the animal took in 
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