Torsion Subgroup of Mapping class group.

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What is the cardinality of finite order elements in Mapping class group of a surface $S_{g,n}$ of genus g and n boundary components.

1) If it is infinite then how can I generate a collection of finite order elements?

2)I know that any finite subgroup is of cardinality at most $84(g-1)$ and I also know that there are finitely many conjugacy classes of finite subgroup. But what about the number of subgroups in each conjugacy class?