162 University of California Publications in Zoology. [Vol. 6 



abruptly to the left, reaching around the median line of the 

 creature, forming thus a semicircle immediately in front of the 

 nucleus. 



The chain consists of two or three blocks which contain fewer 

 zooids than those of fusiformis-runcinata, and there appears to be 

 no intermediate piece. The end zooids of the blocks are slightly 

 smaller than the middle ones, but none of them are rudimentary 

 as in the other species. The deploying point is similar to that of 

 fusiformis-runcinata. 



Fig. 12. — Surface view of stolon, showing point where segmentation be- 

 gins in chain of S. sonaria-eordiformis. 



Microscopical examination of the segmenting stolon shows 

 that the segmentation stops abruptly (fig. 12) instead of being 

 lost gradually. One block was measured and the average of the 

 two rows taken as for the other species. (A higher power objec- 

 tive was used on account of the small size of the zooids so that 

 one unit here is equal to 0.025 mm. ) The same general scheme for 

 I In' graph is seen as in the other blocks of fusiformis-runcinata 

 as the following figures show (Table III). These figures are 

 plotted in tig. 13. 



TABLE 111. 

 Serial measurements of :i block of .s'. zonaria-cordiformis. 



No. ofzooid No. in No. in 



in series Length Width series Length Width series Length Width 



1 34.0 is..") 9 45.0 23.5 17 50.1 26.0 



2 39.5 21.5 10 45.5 2::. 5 18 51.5 28.0 



3 40.5 22.5 11 45.5 24. II 19 52.0 28.5 



4 4H.5 22.il 12 49.0 24.0 20 51.5 28.5 



5 43.5 22.0 13 49.5 25.5 21 5il.ll 28.5 

 (i 40.il 24.0 14 47.5 23.5 22 49.0 26.5 

 7 44.5 22.5 15 51.5 20.5 23 47.0 22.0 

 S 44.0 23.0 16 50.0 25.5 



