( 201 ) 



3 rd . by investigating for each of these Cff. (10,, 15 3 ) in how many 

 ways its 15 lines break up into three principal Jive-sides 1 ), 



4 th . by imagining for each of these cases (he b lines of each 

 principal five-side as converging to one point and these three 

 points as collinear. 



The number of types of Cff. (10,) amounts, according to the 

 classifications of Kantor 3 ) and Schroeter s ), to ten, to be distinguished 



The Cff. of the diagonals of the 10 Cff. (10,) are reap. 



M By principal n-side of a Gf. Martinetti and in. Vries anderstand a group of 

 n Cf-lines which contain together once all the Gf-points. 

 2 ) Wiener Sitzungsberichte 84, 1881. 

 :5 ) Gottinger Nachrichten, 1889, N°. 8. 



