9O A. J. GOLDFARB. 



In Fig. 69, the archentera have approximated but not yet fused 

 into one continuous gut. In Fig. 70 the two have unmistakably 

 united into a single continuous gut with no trace of blastopores. 



FIG. 58. 



A similar gastrula drawn from life and drawn at greater mag- 

 nification than the rest is shown in Fig. 71. In a cluster of four 

 gastrulse two have separate guts, two have united ones, Fig. 72. 

 Instead of fusing end to end, the archentera may unite near 

 their middle as in Fig. 73, or the blastopores with or without 

 parts of the archentera may be united as in Figs. 74, 75 and 76. 

 If one were to suppose the fusion of two archentera side to side, 

 as suggested by the preceding figure, one would anticipate the 

 single giant archenteron shown in Figs. 77 and 78. 



