In the expansion of $\left( x + \frac { 1 } { x ^ { 3 } } \right) ^ { 4 }$, what is the coefficient of $\frac { 1 } { x ^ { 4 } }$? [4 points]\\ (1) 4\\ (2) 6\\ (3) 8\\ (4) 10\\ (5) 12