141 



Woods, H., Elementary Paleontology for geological Students. Cambridge. 



80. With Illustrat. 

 Woodward, Arthur Smith, Some cretaceous pycnodont Fishes. 1. On 



Athrodon. 1 PI. Geolog. Magaz., N. 352, N. S. Decade 3 Y. 10 N. 10 



p. 433—436; N. 353 K 11 p. 481— 487. 

 Wood-ward, A. Smith, On the Dentition of a gigantic extinct Species 



of Myliobatis from the lower tertiary Formation of Egypt. (S. Cap. 9b.) 

 v. Zittel, A., The geological Development, Descent and Distribution of 



the Mammalia. (Continued.) Geolog. Magaz., N. 352, N. S. Decade 3 



V. 10 N. 10 p. 455—469; N. 353 N. 11 p. 501—504. 



In der oben (Cap. 4) angeführten Broschüre protestirt G. Pritsch 

 als Anatom und Kenner des normalen menschlichen Körpers gegen die 

 Verunstaltungen desselben durch die sog. Naturalisten in der Malerei, 

 teilweise auch der Bildhauerei. Der Verfasser wird gewiß bei Sachver- 

 ständigen nur Zustimmung finden ; daß er gegen die Mode und Mache in 

 Künstlerkreisen und im großen Publikum etwas ausrichten werde, ist damit 

 allerdings nicht gesagt. B. 



Aufsätze. 



Nachdruck verboten. 



Experimental Studies on Echinoderm Eggs. 



By T. H. Morgan, Ph. D., Bryn Mawr College. 

 With 4 figures. 



The results of these experiments may be considered under three 

 heads: I. Experiments on Arbacia punctulata. II. Experiments on 

 Asterias Forbesii. III. Experiments on crossing Arbacia and Asterias. 



I. 



Normal Cleavage. The egg nucleus is excentric and relatively 

 small, and although both living and preserved eggs have been repeat- 

 edly studied, no polar globules have been found or any trace of polar 

 spindles. The polar bodies must therefore have been extruded while 

 the eggs were still in the ovaries. Several observations support this 

 view, particularly the observation showing that the spermatozoon 

 reaches the egg nucleus in about fifteen minutes after fertilization and 

 flattens out against the nuclear membrane as described by Fol. The 

 segmentation-nucleus is always very excentric in position. The cleav- 

 eage of the egg of Arbacia agrees with that of the European Echinus. 



