By inadvertciicc of tlie printers, the micle(ili in Fi^'s. 8, 9, 11, 

 lo, Iß, 17, 18, 19, 20, 23, and 24 are represented either as lyino- 

 outside the nuclei or quite eccentrically in Tliem, whereas they 

 ou<i'ht to occupy more central positions. Their true positions are 

 indicated in most of the fi<,aires hy weakly shaded dots. 



