设数列\(\{a _{n} \}\)的前\(n\)项和为\(S _{n}\)，\(a _{1} =-3\)，\(a _{2} =-1.\)若数列\(\{ \dfrac {S_{n}}{n}\}\)为等差数列．
\((1)\)求数列\(\{a _{n} \}\)的通项公式\(a _{n}\)；
\((2)\)设数列\(\{ \dfrac {1}{a_{n}\cdot a_{n-1}}\}\)的前\(n\)项和为\(T _{n}\)，若对\(∀n∈N ^{*}\)都有\(T _{n} > m\)成立，求实数\(m\)的取值范围．