EXPLANATION OF PLATES 
All figures made with the aid of Abbe camera lugida. Those of living eggs in 
outline only. Details supplied free hand. No attempt has been made to give 
exact magnification of living eggs, the erratic shapes making this extremely diffi- 
cult. ' 
PLATE I 
EXPLANATION OF FIGURES 
1 to 4 Pennaria tiarella. Varying aspects of cleavage in early phases, as a 
basis for comparing that of Pennaria australis. p. protoplasmic connective or 
strand; a very common feature in these eggs. x, a blastomere of second cleavage. 
In fig. 3 it will be noted that this blastomere segments more rapidly than the 
lower. This is very common, and continues in fig. 4. 
5 to8 Pennaria australis. Cleavage here resembles in a marked degree that 
of the preceding species. 
9 to 1lb Hydractinia echinata. An extremely erratic cleavage. In fig. 10 
are shown several interesting features, viz. the blastomeres at z, y, z. At fig. 11 
they are shown in a later stage, in which z and y are just becoming detached. 
Their later history is shown in figs. 11, a and b. 
544 
