AND INHERITANCE IN PEDIASTRUM. 



381 



its longest side away from the center of the colony. In the case of 

 the central cell we have a trapezoid with its longest side connecting 

 the apices of the basal lobes. As in P. Boryanum, five of the outer 

 cells stand radially outward from the five cells of series II. and five 

 stand radially opposite the surfaces of contact of the cells of 

 series II. 



Cells eight and sixteen, nine and fifteen, ten and fourteen, eleven 

 and thirteen are paired to the right and left of the axis of the col- 



FiG. 6. Fig. 7. 



Fig. 6. Pediastruni asperum. Very tj^pical colony organization as de- 

 scribed for Fig. 5. This colony served as the model for the type diagram for 

 the species given in Fig. 7. X about 325. 



Fig. 7. Type diagram for P. aspcriim. Angles of intersection of all the 

 walls made 120°. Intercellular spaces and peripheral spines sketched free- 

 hand from the colony shown in Fig. 6. Numbering of cells and lettering of 

 angles as in diagram of P. Boryamtm, fig. 35. 



ony. The adaptive and symmetrical adjustment by which, with the 

 products of cellular bipartition to be grouped, we get five instead 

 of six cells in series II., thus leaving ten for series III., which can 

 be so spaced as to place one cell opposite each cell of series II. and 

 one cell opposite the surface of contact of each pair of cells in series 



