518 MEMOIRS OF THE InIATIONAL ACADEMY OF SCIENCES. 



Plate XXVIII. 



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

 ing nuclear body in clear area. x277. -Ji 



Fig. 23. Swollen, probably degenerating, elements, from segmenting egg of ^-1. minor. x277. "^ 



Fig. 24. Section through base of yolk pyramid of c^g of PaUemonetes vulgaris. About sixty-four 

 cells preseut. x 277. 



Figs. 25, 2(). Two successive sections through clear area in segmenting egg of Alpheus minor, 

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



Fig. 27. Part of section through segmenting egg of Pontnnia dome.itica, before cleavage of the 

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

 'x277. 



Fig. 28. Part of section of an Alpheus egg in same stage as that shown in Fig. 9. Cell dividing 

 indirectly and in horizontal plane. x277. 



Fig. 29. Section ofegg of ^Zp'*^*** *"**^'"'? pr^b^^^y ***''**'*''* •'***'^S"iP"tation. x277. 



Fig. 30. Enlarged view of cell .r. and part of section shown in Fig, 9. x277. 



REFERENCE LETTERS. 



Ch., egg nieniliraues. 



N., nucleus. 



P. A., protoplasmic area. 



r. N., periuuclear protoplasm. 



SC, (SC'-J, degenerating cell products. 



T, yolk. ~ 



T. B., .volk ball. 



y. S., yolk sphere. 



Vac, vacuole. 



