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Forbes, H. O., On some Points in the Anatomy of a Species of Sea-bear 
caught of Sumner, Canterbury, New Zealand, with Notes on the New 
Zealand Eured Seals. Abstract. Transactions and Proceedings of the 
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S. 198— 200. 
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Knochen des Schädels und der Wangen, Kiemenbogenskelett, Schulter- 
gürtel, Becken, Integument und innere Organe. München, 1892. 8°. 
39 SS. 2 Tafeln. Inaug.-Diss. 
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und Tetragonolepiden. (S. Kap. 6a.) 
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and Africa. Geological Society, June 22, 1892. The Annals and Ma- 
gazine of Natural History, Series VI, Vol. X, 1892, Nr. 57, September, 
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Aufsätze. 
Nachdruck verboten. 
On Multiple and Partial Development in Amphioxus. 
By Epmunp B. Wırson, Columbia College, New York. 
With: 11 figures. 
1: 
While studying the cleavage of the ovum of Amphioxus, at Faro, 
I was struck by the fact that the 16-celled stage occasionally appeared 
to be double, as if consisting of two 8-celled embryos united along 
the line of the first cleavage. A study of these double embryos sug- 
gested that some disturbance of the 2-celled stage might have caused 
each of the two blastomeres to enter upon an independent course 
of development, and I was thus led to experiment with 2-celled stages 
by Driescu’s ingenious method (adapted from the brothers HERTWIG) 
of shaking apart the blastomeres. The experiments, successful from 
the first attempt and often repeated afterwards under various con- 
ditions, showed that twin and double embryos could thus be produced 
in great numbers and with perfect ease. As in Echinus, complete 
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