518 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 



PLATE XXVTTI. 



FIG. 22. Part of section of segmenting egg of Alpheus 'minor from Beaufort, North Carolina, show- 

 ing nuclear body in clear area. x277. 



FIG. 23. Swollen, probably degenerating, elements, from segmenting egg of A. minor. x277. 

 FIG. 24. Section through base of yolk pyramid of egg of Palatnonetex rulgarin. About sixty-four 



cells present. x'-'77. 

 FIGS. 25, 2G. Two successive sections through clear area in segmenting egg of Alpheus minor, 



showing degenerative products and nuclear bodies in process of breaking up. x277. 

 FIG. 27. Part of section through segmenting egg of Pontonia domestica, before cleavage of the 



yolk. The egg contains three nuclei, one of which is seen to be in karyokiuesis. 



X277. 

 FIG. 28. Part of section of an Alpheus egg in same stage as that shown in Fig. It. Cell dividing 



indirectly and in horizontal plane. x277. 



FIG. 29. Section of egg of Alfiheus minor, probably at close of segmentation. x277. 

 FIG. 30. Enlarged view of cell .*. and part of section shown in Fig. 9. x277. 



REFERENCE LETTERS. 



Ch., egg membrane!!. 

 _V., nucleus. 



/'. A., protoplasmic area. 

 /'. .iV., perinuclear protoplasm. 

 SC, SC'- 5 , degenerating cell products. 

 Y, yolk. 

 1'. B., yolk hall. 

 .1'. 6., yolk sphere. 

 Vac., vacuole. 



