82 J. F. McCLENDON. 



PLATE II. 



(Figs. 19-24, Lamargus muricatus Kroyer.} 



FIG. 19. First cleavage spindle, prophase. 



FIG. 20. First cleavage spindle, metaphase. 



FIG. 21. Early prophase of second cleavage. To the right, below, is a highly 

 magnified section of the centrosomes in which the centrodesmus and nucleus of the 

 yolk cell are shown. 



FIG. 22. A little later prophase of the same. In the protoplasmic cell the nuclear 

 membrane has begun to dissolve. 



FIG. 23. Later prophase showing the elongation of the nucleus of the yolk cell. 

 Viewed from the animal pole. 



FIG. 24. Late prophase (the protoplasmic cell is in the metaphase) viewed from 

 the vegetal pole. 



figs. 25-30, The Dichelestid. All eggs viewed from vegetal pole, ) 



FIG. 25. Anaphase of the first cleavage (fixation poor?). 



FIG. 26. Two cell stage. The protoplasmic cell is in the anaphase of the second 

 cleavage. 



FIG. 27. Anaphase of the second cleavage viewed from the vegetal pole (the 

 protoplasmic cell is in the telophase). 



FIG. 28. Prophase of third cleavage. 



FIG. 29. Late prophase of fourth cleavage a 4 - 2 , 3 4 - 2 and c 4 - 2 are almost completely 

 hidden by cells lying over them. 



FIG. 30. Spindle in the yolk cell, metaphase of fourth cleavage, from two con- 

 secutive sections and magnified more highly than Fig. 29. Stained with safranin- 

 gentian-violet. The distinctness of the "centrosomes" is exaggerated. The dark 

 granules on the astral rays of the sphere to the right are lumps of hyaloplasm. The 

 delicate network of hyaloplasm between the yolk spherules is represented by dotted 

 lines but the yolk itself is not shown. 



