The format is:
List of 50
\$ 1 :`data.frame': 1000 obs. of 6 variables:
..\$ class: int [1:1000] -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 ...
..\$ F1 : num [1:1000] 2.352 -0.295 1.000 -0.133 -0.774 ...
..\$ F2 : num [1:1000] -1.56 -2.08 1.59 -1.39 0.25 ...
..\$ F3 : num [1:1000] -1.058 0.355 1.779 2.281 1.486 ...
..\$ F4 : num [1:1000] -0.0382 2.2957 -1.8081 1.5588 -3.0523 ...
..\$ f : Factor w/ 50 levels "1","2","3","4",..: 1 1 1 1 1 1 1 1 1 1 ...
... and then 49 similar ones.